20277737561 has 2 divisors, whose sum is σ = 20277737562. Its totient is φ = 20277737560.

The previous prime is 20277737539. The next prime is 20277737563. The reversal of 20277737561 is 16573777202.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11789616400 + 8488121161 = 108580^2 + 92131^2 .

It is a cyclic number.

It is not a de Polignac number, because 20277737561 - 2⁶ = 20277737497 is a prime.

It is a super-2 number, since 2×20277737561² (a number of 21 digits) contains 22 as substring.

Together with 20277737563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20277737563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10138868780 + 10138868781.

It is an arithmetic number, because the mean of its divisors is an integer number (10138868781).

Almost surely, 2^20277737561 is an apocalyptic number.

It is an amenable number.

20277737561 is a deficient number, since it is larger than the sum of its proper divisors (1).

20277737561 is an equidigital number, since it uses as much as digits as its factorization.

20277737561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864360, while the sum is 47.

The spelling of 20277737561 in words is "twenty billion, two hundred seventy-seven million, seven hundred thirty-seven thousand, five hundred sixty-one".