21387004 has 6 divisors (see below), whose sum is σ = 37427264. Its totient is φ = 10693500.

The previous prime is 21387001. The next prime is 21387059. The reversal of 21387004 is 40078312.

It is a self number, because there is not a number n which added to its sum of digits gives 21387004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21387001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2673372 + ... + 2673379.

Almost surely, 2^21387004 is an apocalyptic number.

It is an amenable number.

21387004 is a deficient number, since it is larger than the sum of its proper divisors (16040260).

21387004 is a wasteful number, since it uses less digits than its factorization.

21387004 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5346755 (or 5346753 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 21387004 is about 4624.6085239726. The cubic root of 21387004 is about 277.5768972294.

The spelling of 21387004 in words is "twenty-one million, three hundred eighty-seven thousand, four".