21156910 has 16 divisors (see below), whose sum is σ = 38362896. Its totient is φ = 8400448.

The previous prime is 21156907. The next prime is 21156913. The reversal of 21156910 is 1965112.

21156910 = 1019² + 1020² + ... + 1038².

It is an interprime number because it is at equal distance from previous prime (21156907) and next prime (21156913).

It is a super-2 number, since 2×21156910² = 895229681496200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21156913) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6352 + ... + 9091.

It is an arithmetic number, because the mean of its divisors is an integer number (2397681).

Almost surely, 2^21156910 is an apocalyptic number.

21156910 is a deficient number, since it is larger than the sum of its proper divisors (17205986).

21156910 is a wasteful number, since it uses less digits than its factorization.

21156910 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15587.

The product of its (nonzero) digits is 540, while the sum is 25.

The square root of 21156910 is about 4599.6641181721. The cubic root of 21156910 is about 276.5778605638.

It can be divided in two parts, 2115 and 6910, that added together give a square (9025 = 95²).

The spelling of 21156910 in words is "twenty-one million, one hundred fifty-six thousand, nine hundred ten".