21521204 has 24 divisors (see below), whose sum is σ = 38578848. Its totient is φ = 10501920.

The previous prime is 21521183. The next prime is 21521249. The reversal of 21521204 is 40212512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34802 + ... + 35414.

It is an arithmetic number, because the mean of its divisors is an integer number (1607452).

Almost surely, 2^21521204 is an apocalyptic number.

It is an amenable number.

21521204 is a deficient number, since it is larger than the sum of its proper divisors (17057644).

21521204 is a wasteful number, since it uses less digits than its factorization.

21521204 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 815 (or 813 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21521204 is about 4639.0951703969. The cubic root of 21521204 is about 278.1562705067.

Adding to 21521204 its reverse (40212512), we get a palindrome (61733716).

The spelling of 21521204 in words is "twenty-one million, five hundred twenty-one thousand, two hundred four".