77155985961281 has 2 divisors, whose sum is σ = 77155985961282. Its totient is φ = 77155985961280.

The previous prime is 77155985961193. The next prime is 77155985961283. The reversal of 77155985961281 is 18216958955177.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66980147539600 + 10175838421681 = 8184140^2 + 3189959^2 .

It is a cyclic number.

It is not a de Polignac number, because 77155985961281 - 2¹⁰ = 77155985960257 is a prime.

It is a super-2 number, since 2×77155985961281² (a number of 29 digits) contains 22 as substring.

Together with 77155985961283, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 77155985961199 and 77155985961208.

It is not a weakly prime, because it can be changed into another prime (77155985961283) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38577992980640 + 38577992980641.

It is an arithmetic number, because the mean of its divisors is an integer number (38577992980641).

Almost surely, 2^{77155985961281} is an apocalyptic number.

It is an amenable number.

77155985961281 is a deficient number, since it is larger than the sum of its proper divisors (1).

77155985961281 is an equidigital number, since it uses as much as digits as its factorization.

77155985961281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 381024000, while the sum is 74.

The spelling of 77155985961281 in words is "seventy-seven trillion, one hundred fifty-five billion, nine hundred eighty-five million, nine hundred sixty-one thousand, two hundred eighty-one".