77671187408921 has 2 divisors, whose sum is σ = 77671187408922. Its totient is φ = 77671187408920.

The previous prime is 77671187408869. The next prime is 77671187408963. The reversal of 77671187408921 is 12980478117677.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 70461989258896 + 7209198150025 = 8394164^2 + 2684995^2 .

It is a cyclic number.

It is not a de Polignac number, because 77671187408921 - 2¹⁰ = 77671187407897 is a prime.

It is not a weakly prime, because it can be changed into another prime (77671187408981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38835593704460 + 38835593704461.

It is an arithmetic number, because the mean of its divisors is an integer number (38835593704461).

Almost surely, 2^{77671187408921} is an apocalyptic number.

It is an amenable number.

77671187408921 is a deficient number, since it is larger than the sum of its proper divisors (1).

77671187408921 is an equidigital number, since it uses as much as digits as its factorization.

77671187408921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 66382848, while the sum is 68.

The spelling of 77671187408921 in words is "seventy-seven trillion, six hundred seventy-one billion, one hundred eighty-seven million, four hundred eight thousand, nine hundred twenty-one".