21364831 has 4 divisors (see below), whose sum is σ = 21374352. Its totient is φ = 21355312.

The previous prime is 21364817. The next prime is 21364841. The reversal of 21364831 is 13846312.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21364831 - 2⁷ = 21364703 is a prime.

It is a super-2 number, since 2×21364831² = 912912007317122, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21364831.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21364841) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 675 + ... + 6571.

It is an arithmetic number, because the mean of its divisors is an integer number (5343588).

Almost surely, 2^21364831 is an apocalyptic number.

21364831 is a deficient number, since it is larger than the sum of its proper divisors (9521).

21364831 is an equidigital number, since it uses as much as digits as its factorization.

21364831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9520.

The product of its digits is 3456, while the sum is 28.

The square root of 21364831 is about 4622.2106183081. The cubic root of 21364831 is about 277.4809380083.

The spelling of 21364831 in words is "twenty-one million, three hundred sixty-four thousand, eight hundred thirty-one".