21130556 has 12 divisors (see below), whose sum is σ = 37023168. Its totient is φ = 10552512.

The previous prime is 21130511. The next prime is 21130573. The reversal of 21130556 is 65503112.

It is a super-4 number, since 4×21130556⁴ (a number of 30 digits) contains 4444 as substring.

It is a congruent number.

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, 1205 + ... + 6611.

It is an arithmetic number, because the mean of its divisors is an integer number (3085264).

Almost surely, 2^21130556 is an apocalyptic number.

It is an amenable number.

21130556 is a deficient number, since it is larger than the sum of its proper divisors (15892612).

21130556 is a wasteful number, since it uses less digits than its factorization.

21130556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6388 (or 6386 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 23.

The square root of 21130556 is about 4596.7984510962. The cubic root of 21130556 is about 276.4629735678.

Adding to 21130556 its reverse (65503112), we get a palindrome (86633668).

The spelling of 21130556 in words is "twenty-one million, one hundred thirty thousand, five hundred fifty-six".