20561255077 has 16 divisors (see below), whose sum is σ = 22881979008. Its totient is φ = 18316658880.

The previous prime is 20561255063. The next prime is 20561255087. The reversal of 20561255077 is 77055216502.

It is a cyclic number.

It is not a de Polignac number, because 20561255077 - 2²³ = 20552866469 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20561255027) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 458383 + ... + 501235.

It is an arithmetic number, because the mean of its divisors is an integer number (1430123688).

Almost surely, 2^20561255077 is an apocalyptic number.

It is an amenable number.

20561255077 is a deficient number, since it is larger than the sum of its proper divisors (2320723931).

20561255077 is a wasteful number, since it uses less digits than its factorization.

20561255077 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43740.

The product of its (nonzero) digits is 147000, while the sum is 40.

The spelling of 20561255077 in words is "twenty billion, five hundred sixty-one million, two hundred fifty-five thousand, seventy-seven".