21687304 has 16 divisors (see below), whose sum is σ = 41529600. Its totient is φ = 10612752.

The previous prime is 21687301. The next prime is 21687307. The reversal of 21687304 is 40378612.

It is an interprime number because it is at equal distance from previous prime (21687301) and next prime (21687307).

It is not an unprimeable number, because it can be changed into a prime (21687301) 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, 28464 + ... + 29215.

It is an arithmetic number, because the mean of its divisors is an integer number (2595600).

Almost surely, 2^21687304 is an apocalyptic number.

It is an amenable number.

21687304 is a deficient number, since it is larger than the sum of its proper divisors (19842296).

21687304 is a wasteful number, since it uses less digits than its factorization.

21687304 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57732 (or 57728 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 31.

The square root of 21687304 is about 4656.9629588392. The cubic root of 21687304 is about 278.8700379198.

The spelling of 21687304 in words is "twenty-one million, six hundred eighty-seven thousand, three hundred four".