21400900 has 18 divisors (see below), whose sum is σ = 46440170. Its totient is φ = 8560320.

The previous prime is 21400889. The next prime is 21400903. The reversal of 21400900 is 900412.

It can be written as a sum of positive squares in 3 ways, for example, as 1024 + 21399876 = 32^2 + 4626^2 .

It is not an unprimeable number, because it can be changed into a prime (21400903) 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, 106905 + ... + 107104.

Almost surely, 2^21400900 is an apocalyptic number.

21400900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21400900 is an abundant number, since it is smaller than the sum of its proper divisors (25039270).

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

21400900 is a wasteful number, since it uses less digits than its factorization.

21400900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214023 (or 214016 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 21400900 is about 4626.1106774482. The cubic root of 21400900 is about 277.6370018529.

The spelling of 21400900 in words is "twenty-one million, four hundred thousand, nine hundred".