21113421 has 32 divisors (see below), whose sum is σ = 34218240. Its totient is φ = 11321856.

The previous prime is 21113399. The next prime is 21113423. The reversal of 21113421 is 12431112.

It is not a de Polignac number, because 21113421 - 2⁶ = 21113357 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21113421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21113423) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 22065 + ... + 23001.

It is an arithmetic number, because the mean of its divisors is an integer number (1069320).

Almost surely, 2^21113421 is an apocalyptic number.

21113421 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21113421 is a deficient number, since it is larger than the sum of its proper divisors (13104819).

21113421 is a wasteful number, since it uses less digits than its factorization.

21113421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1013.

The product of its digits is 48, while the sum is 15.

The square root of 21113421 is about 4594.9342759173. The cubic root of 21113421 is about 276.3882244050.

Adding to 21113421 its reverse (12431112), we get a palindrome (33544533).

The spelling of 21113421 in words is "twenty-one million, one hundred thirteen thousand, four hundred twenty-one".