21173878080 has 336 divisors, whose sum is σ = 77465553984. Its totient is φ = 5289984000.

The previous prime is 21173878079. The next prime is 21173878087. The reversal of 21173878080 is 8087837112.

21173878080 is a `hidden beast` number, since 2 + 117 + 387 + 80 + 80 = 666.

It is a super-2 number, since 2×21173878080² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21173878087) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 12288099 + ... + 12289821.

It is an arithmetic number, because the mean of its divisors is an integer number (230552244).

Almost surely, 2^21173878080 is an apocalyptic number.

21173878080 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21173878080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38732776992).

21173878080 is an abundant number, since it is smaller than the sum of its proper divisors (56291675904).

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

21173878080 is a wasteful number, since it uses less digits than its factorization.

21173878080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2014 (or 2001 counting only the distinct ones).

The product of its (nonzero) digits is 150528, while the sum is 45.

The spelling of 21173878080 in words is "twenty-one billion, one hundred seventy-three million, eight hundred seventy-eight thousand, eighty".