9931977661 has 2 divisors, whose sum is σ = 9931977662. Its totient is φ = 9931977660.

The previous prime is 9931977617. The next prime is 9931977667. The reversal of 9931977661 is 1667791399.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8499733636 + 1432244025 = 92194^2 + 37845^2 .

It is a cyclic number.

It is not a de Polignac number, because 9931977661 - 2⁷ = 9931977533 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 9931977596 and 9931977605.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9931977667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4965988830 + 4965988831.

It is an arithmetic number, because the mean of its divisors is an integer number (4965988831).

Almost surely, 2^9931977661 is an apocalyptic number.

It is an amenable number.

9931977661 is a deficient number, since it is larger than the sum of its proper divisors (1).

9931977661 is an equidigital number, since it uses as much as digits as its factorization.

9931977661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3857868, while the sum is 58.

The square root of 9931977661 is about 99659.3079496341. The cubic root of 9931977661 is about 2149.5385821418.

The spelling of 9931977661 in words is "nine billion, nine hundred thirty-one million, nine hundred seventy-seven thousand, six hundred sixty-one".