21173878180 has 72 divisors (see below), whose sum is σ = 55027086912. Its totient is φ = 6701175936.

The previous prime is 21173878151. The next prime is 21173878181. The reversal of 21173878180 is 8187837112.

It is a super-2 number, since 2×21173878180² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21173878180.

It is not an unprimeable number, because it can be changed into a prime (21173878181) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 423802 + ... + 471121.

It is an arithmetic number, because the mean of its divisors is an integer number (764265096).

Almost surely, 2^21173878180 is an apocalyptic number.

21173878180 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21173878180 is an abundant number, since it is smaller than the sum of its proper divisors (33853208732).

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

21173878180 is a wasteful number, since it uses less digits than its factorization.

21173878180 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 894965 (or 894950 counting only the distinct ones).

The product of its (nonzero) digits is 150528, while the sum is 46.

The spelling of 21173878180 in words is "twenty-one billion, one hundred seventy-three million, eight hundred seventy-eight thousand, one hundred eighty".