661759967977 has 2 divisors, whose sum is σ = 661759967978. Its totient is φ = 661759967976.

The previous prime is 661759967969. The next prime is 661759968007. The reversal of 661759967977 is 779769957166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 657013998096 + 4745969881 = 810564^2 + 68891^2 .

It is a cyclic number.

It is not a de Polignac number, because 661759967977 - 2³ = 661759967969 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 661759967897 and 661759967906.

It is not a weakly prime, because it can be changed into another prime (661759967377) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330879983988 + 330879983989.

It is an arithmetic number, because the mean of its divisors is an integer number (330879983989).

Almost surely, 2^661759967977 is an apocalyptic number.

It is an amenable number.

661759967977 is a deficient number, since it is larger than the sum of its proper divisors (1).

661759967977 is an equidigital number, since it uses as much as digits as its factorization.

661759967977 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1890355320, while the sum is 79.

The spelling of 661759967977 in words is "six hundred sixty-one billion, seven hundred fifty-nine million, nine hundred sixty-seven thousand, nine hundred seventy-seven".