21628660670778 has 32 divisors (see below), whose sum is σ = 49471009758720. Its totient is φ = 6175358449200.

The previous prime is 21628660670719. The next prime is 21628660670783. The reversal of 21628660670778 is 87707606682612.

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, 177391888 + ... + 177513771.

It is an arithmetic number, because the mean of its divisors is an integer number (1545969054960).

Almost surely, 2^{21628660670778} is an apocalyptic number.

21628660670778 is an abundant number, since it is smaller than the sum of its proper divisors (27842349087942).

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

21628660670778 is a wasteful number, since it uses less digits than its factorization.

21628660670778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 354907122.

The product of its (nonzero) digits is 113799168, while the sum is 66.

The spelling of 21628660670778 in words is "twenty-one trillion, six hundred twenty-eight billion, six hundred sixty million, six hundred seventy thousand, seven hundred seventy-eight".