21415664 has 10 divisors (see below), whose sum is σ = 41492880. Its totient is φ = 10707824.

The previous prime is 21415661. The next prime is 21415721. The reversal of 21415664 is 46651412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21415661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 669224 + ... + 669255.

It is an arithmetic number, because the mean of its divisors is an integer number (4149288).

Almost surely, 2^21415664 is an apocalyptic number.

It is an amenable number.

21415664 is a deficient number, since it is larger than the sum of its proper divisors (20077216).

21415664 is a wasteful number, since it uses less digits than its factorization.

21415664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1338487 (or 1338481 counting only the distinct ones).

The product of its digits is 5760, while the sum is 29.

The square root of 21415664 is about 4627.7061272298. The cubic root of 21415664 is about 277.7008323530.

The spelling of 21415664 in words is "twenty-one million, four hundred fifteen thousand, six hundred sixty-four".