21423831 has 16 divisors (see below), whose sum is σ = 33559680. Its totient is φ = 11985120.

The previous prime is 21423827. The next prime is 21423863. The reversal of 21423831 is 13832412.

It is not a de Polignac number, because 21423831 - 2² = 21423827 is a prime.

It is a super-2 number, since 2×21423831² = 917961069433122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21423631) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24541 + ... + 25398.

It is an arithmetic number, because the mean of its divisors is an integer number (2097480).

Almost surely, 2^21423831 is an apocalyptic number.

21423831 is a deficient number, since it is larger than the sum of its proper divisors (12135849).

21423831 is a wasteful number, since it uses less digits than its factorization.

21423831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49966.

The product of its digits is 1152, while the sum is 24.

The square root of 21423831 is about 4628.5884457359. The cubic root of 21423831 is about 277.7361288608.

The spelling of 21423831 in words is "twenty-one million, four hundred twenty-three thousand, eight hundred thirty-one".