21088400 has 30 divisors (see below), whose sum is σ = 50665842. Its totient is φ = 8435200.

The previous prime is 21088393. The next prime is 21088421. The reversal of 21088400 is 488012.

It can be written as a sum of positive squares in 3 ways, for example, as 1936 + 21086464 = 44^2 + 4592^2 .

It is a super-2 number, since 2×21088400² = 889441229120000, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 25961 + ... + 26760.

Almost surely, 2^21088400 is an apocalyptic number.

21088400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21088400 is an abundant number, since it is smaller than the sum of its proper divisors (29577442).

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

21088400 is a wasteful number, since it uses less digits than its factorization.

21088400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52739 (or 52728 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 23.

The square root of 21088400 is about 4592.2107965554. The cubic root of 21088400 is about 276.2790009343.

The spelling of 21088400 in words is "twenty-one million, eighty-eight thousand, four hundred".