77961997121 has 2 divisors, whose sum is σ = 77961997122. Its totient is φ = 77961997120.

The previous prime is 77961997097. The next prime is 77961997163. The reversal of 77961997121 is 12179916977.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 68134050625 + 9827946496 = 261025^2 + 99136^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77961997121 is a prime.

It is not a weakly prime, because it can be changed into another prime (77961997181) 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, 38980998560 + 38980998561.

It is an arithmetic number, because the mean of its divisors is an integer number (38980998561).

Almost surely, 2^77961997121 is an apocalyptic number.

It is an amenable number.

77961997121 is a deficient number, since it is larger than the sum of its proper divisors (1).

77961997121 is an equidigital number, since it uses as much as digits as its factorization.

77961997121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3000564, while the sum is 59.

The spelling of 77961997121 in words is "seventy-seven billion, nine hundred sixty-one million, nine hundred ninety-seven thousand, one hundred twenty-one".