21130504 has 8 divisors (see below), whose sum is σ = 39619710. Its totient is φ = 10565248.

The previous prime is 21130481. The next prime is 21130511. The reversal of 21130504 is 40503112.

It can be written as a sum of positive squares in only one way, i.e., 15225604 + 5904900 = 3902^2 + 2430^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1320649 + ... + 1320664.

Almost surely, 2^21130504 is an apocalyptic number.

It is an amenable number.

21130504 is a deficient number, since it is larger than the sum of its proper divisors (18489206).

21130504 is a wasteful number, since it uses less digits than its factorization.

21130504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2641319 (or 2641315 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21130504 is about 4596.7927949822. The cubic root of 21130504 is about 276.4627467858.

Adding to 21130504 its reverse (40503112), we get a palindrome (61633616).

The spelling of 21130504 in words is "twenty-one million, one hundred thirty thousand, five hundred four".