77938946557 has 2 divisors, whose sum is σ = 77938946558. Its totient is φ = 77938946556.

The previous prime is 77938946537. The next prime is 77938946651. The reversal of 77938946557 is 75564983977.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 51154678276 + 26784268281 = 226174^2 + 163659^2 .

It is a cyclic number.

It is not a de Polignac number, because 77938946557 - 2²³ = 77930557949 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77938946507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38969473278 + 38969473279.

It is an arithmetic number, because the mean of its divisors is an integer number (38969473279).

Almost surely, 2^77938946557 is an apocalyptic number.

It is an amenable number.

77938946557 is a deficient number, since it is larger than the sum of its proper divisors (1).

77938946557 is an equidigital number, since it uses as much as digits as its factorization.

77938946557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 400075200, while the sum is 70.

The spelling of 77938946557 in words is "seventy-seven billion, nine hundred thirty-eight million, nine hundred forty-six thousand, five hundred fifty-seven".