21120000 has 220 divisors, whose sum is σ = 76737936. Its totient is φ = 5120000.

The previous prime is 21119999. The next prime is 21120017. The reversal of 21120000 is 2112.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (220).

It is a Harshad number since it is a multiple of its sum of digits (6).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1919995 + ... + 1920005.

Almost surely, 2^21120000 is an apocalyptic number.

21120000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21120000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38368968).

21120000 is an abundant number, since it is smaller than the sum of its proper divisors (55617936).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21120000 is an equidigital number, since it uses as much as digits as its factorization.

21120000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54 (or 21 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 6.

The square root of 21120000 is about 4595.6501172304. The cubic root of 21120000 is about 276.4169292004.

Adding to 21120000 its reverse (2112), we get a palindrome (21122112).

Multiplying 21120000 by its reverse (2112), we get a square (44605440000 = 211200²).

21120000 divided by its reverse (2112) gives a 4-th power (10000 = 10⁴).

It can be divided in two parts, 21 and 120000, that added together give a palindrome (120021).

The spelling of 21120000 in words is "twenty-one million, one hundred twenty thousand".