21895764 has 24 divisors (see below), whose sum is σ = 55735008. Its totient is φ = 6635040.

The previous prime is 21895759. The next prime is 21895787. The reversal of 21895764 is 46759812.

It is a super-2 number, since 2×21895764² = 958848962287392, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 82807 + ... + 83070.

It is an arithmetic number, because the mean of its divisors is an integer number (2322292).

Almost surely, 2^21895764 is an apocalyptic number.

It is an amenable number.

21895764 is an abundant number, since it is smaller than the sum of its proper divisors (33839244).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21895764 is a wasteful number, since it uses less digits than its factorization.

21895764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165895 (or 165893 counting only the distinct ones).

The product of its digits is 120960, while the sum is 42.

The square root of 21895764 is about 4679.2909719315. The cubic root of 21895764 is about 279.7606968975.

The spelling of 21895764 in words is "twenty-one million, eight hundred ninety-five thousand, seven hundred sixty-four".