21113021 has 4 divisors (see below), whose sum is σ = 21201600. Its totient is φ = 21024444.

The previous prime is 21113017. The next prime is 21113023. The reversal of 21113021 is 12031112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21113021 - 2² = 21113017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21112993 and 21113011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21113023) 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 3 ways as a sum of consecutive naturals, for example, 43931 + ... + 44408.

It is an arithmetic number, because the mean of its divisors is an integer number (5300400).

Almost surely, 2^21113021 is an apocalyptic number.

It is an amenable number.

21113021 is a deficient number, since it is larger than the sum of its proper divisors (88579).

21113021 is an equidigital number, since it uses as much as digits as its factorization.

21113021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88578.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 21113021 is about 4594.8907495173. The cubic root of 21113021 is about 276.3864789751.

Adding to 21113021 its reverse (12031112), we get a palindrome (33144133).

The spelling of 21113021 in words is "twenty-one million, one hundred thirteen thousand, twenty-one".