21180388640 has 48 divisors (see below), whose sum is σ = 50066009280. Its totient is φ = 8467526400.

The previous prime is 21180388639. The next prime is 21180388651. The reversal of 21180388640 is 4688308112.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 265415 + ... + 335865.

It is an arithmetic number, because the mean of its divisors is an integer number (1043041860).

Almost surely, 2^21180388640 is an apocalyptic number.

21180388640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21180388640 is an abundant number, since it is smaller than the sum of its proper divisors (28885620640).

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

21180388640 is a wasteful number, since it uses less digits than its factorization.

21180388640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72345 (or 72337 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 41.

The spelling of 21180388640 in words is "twenty-one billion, one hundred eighty million, three hundred eighty-eight thousand, six hundred forty".