20955556978638 has 32 divisors (see below), whose sum is σ = 42089094291456. Its totient is φ = 6955581778848.

The previous prime is 20955556978589. The next prime is 20955556978667. The reversal of 20955556978638 is 83687965555902.

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, 6029370 + ... + 8846717.

It is an arithmetic number, because the mean of its divisors is an integer number (1315284196608).

Almost surely, 2^{20955556978638} is an apocalyptic number.

20955556978638 is an abundant number, since it is smaller than the sum of its proper divisors (21133537312818).

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

20955556978638 is a wasteful number, since it uses less digits than its factorization.

20955556978638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14877088.

The product of its (nonzero) digits is 4898880000, while the sum is 78.

The spelling of 20955556978638 in words is "twenty trillion, nine hundred fifty-five billion, five hundred fifty-six million, nine hundred seventy-eight thousand, six hundred thirty-eight".