21634764 has 12 divisors (see below), whose sum is σ = 50481144. Its totient is φ = 7211584.

The previous prime is 21634741. The next prime is 21634799. The reversal of 21634764 is 46743612.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 901437 + ... + 901460.

It is an arithmetic number, because the mean of its divisors is an integer number (4206762).

Almost surely, 2^21634764 is an apocalyptic number.

It is an amenable number.

21634764 is an abundant number, since it is smaller than the sum of its proper divisors (28846380).

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

21634764 is a wasteful number, since it uses less digits than its factorization.

21634764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1802904 (or 1802902 counting only the distinct ones).

The product of its digits is 24192, while the sum is 33.

The square root of 21634764 is about 4651.3185227417. The cubic root of 21634764 is about 278.6446575212.

It can be divided in two parts, 216 and 34764, that added together give a triangular number (34980 = T₂₆₄).

The spelling of 21634764 in words is "twenty-one million, six hundred thirty-four thousand, seven hundred sixty-four".