21646609880 has 64 divisors (see below), whose sum is σ = 56367360000. Its totient is φ = 7327741824.

The previous prime is 21646609879. The next prime is 21646609913. The reversal of 21646609880 is 8890664612.

It is a happy number.

It is a super-2 number, since 2×21646609880² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 467180 + ... + 511419.

It is an arithmetic number, because the mean of its divisors is an integer number (880740000).

Almost surely, 2^21646609880 is an apocalyptic number.

21646609880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21646609880 is an abundant number, since it is smaller than the sum of its proper divisors (34720750120).

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

21646609880 is a wasteful number, since it uses less digits than its factorization.

21646609880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 978696 (or 978692 counting only the distinct ones).

The product of its (nonzero) digits is 995328, while the sum is 50.

The spelling of 21646609880 in words is "twenty-one billion, six hundred forty-six million, six hundred nine thousand, eight hundred eighty".