21634746660 has 36 divisors (see below), whose sum is σ = 65625398748. Its totient is φ = 5769265728.

The previous prime is 21634746629. The next prime is 21634746667. The reversal of 21634746660 is 6664743612.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 9982407744 + 11652338916 = 99912^2 + 107946^2 .

It is a tau number, because it is divible by the number of its divisors (36).

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 (21634746667) 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, 60096339 + ... + 60096698.

It is an arithmetic number, because the mean of its divisors is an integer number (1822927743).

Almost surely, 2^21634746660 is an apocalyptic number.

21634746660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21634746660 is an abundant number, since it is smaller than the sum of its proper divisors (43990652088).

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

21634746660 is a wasteful number, since it uses less digits than its factorization.

21634746660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120193052 (or 120193047 counting only the distinct ones).

The product of its (nonzero) digits is 870912, while the sum is 45.

The spelling of 21634746660 in words is "twenty-one billion, six hundred thirty-four million, seven hundred forty-six thousand, six hundred sixty".