21868100 has 18 divisors (see below), whose sum is σ = 47453994. Its totient is φ = 8747200.

The previous prime is 21868097. The next prime is 21868109. The reversal of 21868100 is 186812.

It can be written as a sum of positive squares in 3 ways, for example, as 264196 + 21603904 = 514^2 + 4648^2 .

It is a super-2 number, since 2×21868100² = 956427595220000, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21868100.

It is not an unprimeable number, because it can be changed into a prime (21868109) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 109241 + ... + 109440.

It is an arithmetic number, because the mean of its divisors is an integer number (2636333).

Almost surely, 2^21868100 is an apocalyptic number.

21868100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21868100 is an abundant number, since it is smaller than the sum of its proper divisors (25585894).

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

21868100 is a wasteful number, since it uses less digits than its factorization.

21868100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218695 (or 218688 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 26.

The square root of 21868100 is about 4676.3340342623. The cubic root of 21868100 is about 279.6428268901.

The spelling of 21868100 in words is "twenty-one million, eight hundred sixty-eight thousand, one hundred".