20861342778 has 16 divisors (see below), whose sum is σ = 41753090016. Its totient is φ = 6948713520.

The previous prime is 20861342737. The next prime is 20861342783. The reversal of 20861342778 is 87724316802.

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, 1257928 + ... + 1274403.

It is an arithmetic number, because the mean of its divisors is an integer number (2609568126).

Almost surely, 2^20861342778 is an apocalyptic number.

20861342778 is an abundant number, since it is smaller than the sum of its proper divisors (20891747238).

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

20861342778 is a wasteful number, since it uses less digits than its factorization.

20861342778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2533709.

The product of its (nonzero) digits is 903168, while the sum is 48.

The spelling of 20861342778 in words is "twenty billion, eight hundred sixty-one million, three hundred forty-two thousand, seven hundred seventy-eight".