21872810 has 16 divisors (see below), whose sum is σ = 40287456. Its totient is φ = 8545488.

The previous prime is 21872801. The next prime is 21872827. The reversal of 21872810 is 1827812.

It is a super-2 number, since 2×21872810² = 956839634592200, which contains 22 as substring.

It is an unprimeable number.

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, 25004 + ... + 25863.

It is an arithmetic number, because the mean of its divisors is an integer number (2517966).

Almost surely, 2^21872810 is an apocalyptic number.

21872810 is a deficient number, since it is larger than the sum of its proper divisors (18414646).

21872810 is a wasteful number, since it uses less digits than its factorization.

21872810 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50917.

The product of its (nonzero) digits is 1792, while the sum is 29.

The square root of 21872810 is about 4676.8376067595. The cubic root of 21872810 is about 279.6629021468.

The spelling of 21872810 in words is "twenty-one million, eight hundred seventy-two thousand, eight hundred ten".