20561726377 has 4 divisors (see below), whose sum is σ = 20563929936. Its totient is φ = 20559522820.

The previous prime is 20561726357. The next prime is 20561726387. The reversal of 20561726377 is 77362716502.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20561726377 - 2²³ = 20553337769 is a prime.

It is a super-2 number, since 2×20561726377² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20561726327) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1087723 + ... + 1106464.

It is an arithmetic number, because the mean of its divisors is an integer number (5140982484).

Almost surely, 2^20561726377 is an apocalyptic number.

It is an amenable number.

20561726377 is a deficient number, since it is larger than the sum of its proper divisors (2203559).

20561726377 is an equidigital number, since it uses as much as digits as its factorization.

20561726377 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2203558.

The product of its (nonzero) digits is 740880, while the sum is 46.

The spelling of 20561726377 in words is "twenty billion, five hundred sixty-one million, seven hundred twenty-six thousand, three hundred seventy-seven".