21390604 has 6 divisors (see below), whose sum is σ = 37433564. Its totient is φ = 10695300.

The previous prime is 21390601. The next prime is 21390613. The reversal of 21390604 is 40609312.

It is not an unprimeable number, because it can be changed into a prime (21390601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2673822 + ... + 2673829.

Almost surely, 2^21390604 is an apocalyptic number.

It is an amenable number.

21390604 is a deficient number, since it is larger than the sum of its proper divisors (16042960).

21390604 is a wasteful number, since it uses less digits than its factorization.

21390604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5347655 (or 5347653 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 21390604 is about 4624.9977297292. The cubic root of 21390604 is about 277.5924708735.

Adding to 21390604 its reverse (40609312), we get a palindrome (61999916).

It can be divided in two parts, 21 and 390604, that added together give a 8-th power (390625 = 5⁸).

The spelling of 21390604 in words is "twenty-one million, three hundred ninety thousand, six hundred four".