20999761564778 has 16 divisors (see below), whose sum is σ = 32268423043584. Its totient is φ = 10243628435040.

The previous prime is 20999761564777. The next prime is 20999761564807. The reversal of 20999761564778 is 87746516799902.

It is not an unprimeable number, because it can be changed into a prime (20999761564777) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3479351 + ... + 7355637.

It is an arithmetic number, because the mean of its divisors is an integer number (2016776440224).

Almost surely, 2^{20999761564778} is an apocalyptic number.

20999761564778 is a deficient number, since it is larger than the sum of its proper divisors (11268661478806).

20999761564778 is a wasteful number, since it uses less digits than its factorization.

20999761564778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3942397.

The product of its (nonzero) digits is 2880541440, while the sum is 80.

The spelling of 20999761564778 in words is "twenty trillion, nine hundred ninety-nine billion, seven hundred sixty-one million, five hundred sixty-four thousand, seven hundred seventy-eight".