21660725650 has 24 divisors (see below), whose sum is σ = 40704308820. Its totient is φ = 8574965760.

The previous prime is 21660725633. The next prime is 21660725651. The reversal of 21660725650 is 5652706612.

It can be written as a sum of positive squares in 6 ways, for example, as 7867867401 + 13792858249 = 88701^2 + 117443^2 .

It is not an unprimeable number, because it can be changed into a prime (21660725651) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2228215 + ... + 2237914.

Almost surely, 2^21660725650 is an apocalyptic number.

21660725650 is a deficient number, since it is larger than the sum of its proper divisors (19043583170).

21660725650 is a wasteful number, since it uses less digits than its factorization.

21660725650 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4466238 (or 4466233 counting only the distinct ones).

The product of its (nonzero) digits is 151200, while the sum is 40.

The spelling of 21660725650 in words is "twenty-one billion, six hundred sixty million, seven hundred twenty-five thousand, six hundred fifty".