21407764 has 12 divisors (see below), whose sum is σ = 42815584. Its totient is φ = 9174744.

The previous prime is 21407717. The next prime is 21407783. The reversal of 21407764 is 46770412.

21407764 is an admirable number.

It is a congruent number.

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, 382254 + ... + 382309.

Almost surely, 2^21407764 is an apocalyptic number.

It is an amenable number.

21407764 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21407764 is a wasteful number, since it uses less digits than its factorization.

21407764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 764574 (or 764572 counting only the distinct ones).

The product of its (nonzero) digits is 9408, while the sum is 31.

The square root of 21407764 is about 4626.8524938666. The cubic root of 21407764 is about 277.6666812383. Note that the first 4 decimals are identical.

The spelling of 21407764 in words is "twenty-one million, four hundred seven thousand, seven hundred sixty-four".