21656065600 has 189 divisors, whose sum is σ = 57906415683. Its totient is φ = 7967831040.

The previous prime is 21656065597. The next prime is 21656065601. The reversal of 21656065600 is 656065612.

The square root of 21656065600 is 147160.

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 5581882944 + 16074182656 = 74712^2 + 126784^2 .

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21656065600.

It is not an unprimeable number, because it can be changed into a prime (21656065601) 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, 76523059 + ... + 76523341.

Almost surely, 2^21656065600 is an apocalyptic number.

21656065600 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21656065600 is the 147160-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21656065600

21656065600 is an abundant number, since it is smaller than the sum of its proper divisors (36250350083).

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

21656065600 is an equidigital number, since it uses as much as digits as its factorization.

21656065600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 614 (or 303 counting only the distinct ones).

The product of its (nonzero) digits is 64800, while the sum is 37.

The spelling of 21656065600 in words is "twenty-one billion, six hundred fifty-six million, sixty-five thousand, six hundred".