21112540 has 24 divisors (see below), whose sum is σ = 45419472. Its totient is φ = 8238720.

The previous prime is 21112433. The next prime is 21112547. The reversal of 21112540 is 4521112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21112547) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12054 + ... + 13693.

It is an arithmetic number, because the mean of its divisors is an integer number (1892478).

Almost surely, 2^21112540 is an apocalyptic number.

21112540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21112540 is an abundant number, since it is smaller than the sum of its proper divisors (24306932).

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

21112540 is a wasteful number, since it uses less digits than its factorization.

21112540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25797 (or 25795 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 21112540 is about 4594.8384084753. The cubic root of 21112540 is about 276.3843800665.

Adding to 21112540 its reverse (4521112), we get a palindrome (25633652).

The spelling of 21112540 in words is "twenty-one million, one hundred twelve thousand, five hundred forty".