21688452900 has 81 divisors (see below), whose sum is σ = 67995101811. Its totient is φ = 5782409280.

The previous prime is 21688452883. The next prime is 21688452901. The reversal of 21688452900 is 925488612.

The square root of 21688452900 is 147270.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 6077449764 + 15611003136 = 77958^2 + 124944^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (21688452901) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 4415646 + ... + 4420554.

Almost surely, 2^21688452900 is an apocalyptic number.

21688452900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21688452900 is the 147270-th square number.

It is an amenable number.

21688452900 is an abundant number, since it is smaller than the sum of its proper divisors (46306648911).

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

21688452900 is an equidigital number, since it uses as much as digits as its factorization.

21688452900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9838 (or 4919 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 45.

The spelling of 21688452900 in words is "twenty-one billion, six hundred eighty-eight million, four hundred fifty-two thousand, nine hundred".