21369831 has 24 divisors (see below), whose sum is σ = 34049520. Its totient is φ = 11878272.

The previous prime is 21369811. The next prime is 21369847. The reversal of 21369831 is 13896312.

It is not a de Polignac number, because 21369831 - 2⁶ = 21369767 is a prime.

It is a super-2 number, since 2×21369831² = 913339353937122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21369792 and 21369801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21369811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3475 + ... + 7403.

It is an arithmetic number, because the mean of its divisors is an integer number (1418730).

Almost surely, 2^21369831 is an apocalyptic number.

21369831 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21369831 is a deficient number, since it is larger than the sum of its proper divisors (12679689).

21369831 is a wasteful number, since it uses less digits than its factorization.

21369831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3983 (or 3976 counting only the distinct ones).

The product of its digits is 7776, while the sum is 33.

The square root of 21369831 is about 4622.7514534095. The cubic root of 21369831 is about 277.5025825585.

The spelling of 21369831 in words is "twenty-one million, three hundred sixty-nine thousand, eight hundred thirty-one".