21002868 has 24 divisors (see below), whose sum is σ = 54452160. Its totient is φ = 7000920.

The previous prime is 21002857. The next prime is 21002881. The reversal of 21002868 is 86820012.

It is a super-2 number, since 2×21002868² = 882240928450848, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

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, 97128 + ... + 97343.

It is an arithmetic number, because the mean of its divisors is an integer number (2268840).

Almost surely, 2^21002868 is an apocalyptic number.

It is an amenable number.

21002868 is an abundant number, since it is smaller than the sum of its proper divisors (33449292).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21002868 is a wasteful number, since it uses less digits than its factorization.

21002868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194484 (or 194476 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 21002868 is about 4582.8886087270. Note that the first 3 decimals coincide. The cubic root of 21002868 is about 275.9049767403.

The spelling of 21002868 in words is "twenty-one million, two thousand, eight hundred sixty-eight".