21531304 has 16 divisors (see below), whose sum is σ = 41310720. Its totient is φ = 10515120.

The previous prime is 21531269. The next prime is 21531317. The reversal of 21531304 is 40313512.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30952 + ... + 31639.

It is an arithmetic number, because the mean of its divisors is an integer number (2581920).

Almost surely, 2^21531304 is an apocalyptic number.

It is an amenable number.

21531304 is a deficient number, since it is larger than the sum of its proper divisors (19779416).

21531304 is a wasteful number, since it uses less digits than its factorization.

21531304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62640 (or 62636 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 21531304 is about 4640.1836170565. The cubic root of 21531304 is about 278.1997770404.

Adding to 21531304 its reverse (40313512), we get a palindrome (61844816).

The spelling of 21531304 in words is "twenty-one million, five hundred thirty-one thousand, three hundred four".