77861041321681 has 2 divisors, whose sum is σ = 77861041321682. Its totient is φ = 77861041321680.

The previous prime is 77861041321669. The next prime is 77861041321699. The reversal of 77861041321681 is 18612314016877.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 70587151411456 + 7273889910225 = 8401616^2 + 2697015^2 .

It is a cyclic number.

It is not a de Polignac number, because 77861041321681 - 2²⁷ = 77860907103953 is a prime.

It is a super-2 number, since 2×77861041321681² (a number of 29 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (77861041321181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38930520660840 + 38930520660841.

It is an arithmetic number, because the mean of its divisors is an integer number (38930520660841).

Almost surely, 2^{77861041321681} is an apocalyptic number.

It is an amenable number.

77861041321681 is a deficient number, since it is larger than the sum of its proper divisors (1).

77861041321681 is an equidigital number, since it uses as much as digits as its factorization.

77861041321681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2709504, while the sum is 55.

The spelling of 77861041321681 in words is "seventy-seven trillion, eight hundred sixty-one billion, forty-one million, three hundred twenty-one thousand, six hundred eighty-one".