78595921081 has 2 divisors, whose sum is σ = 78595921082. Its totient is φ = 78595921080.

The previous prime is 78595921073. The next prime is 78595921099. The reversal of 78595921081 is 18012959587.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50486045481 + 28109875600 = 224691^2 + 167660^2 .

It is a cyclic number.

It is not a de Polignac number, because 78595921081 - 2³ = 78595921073 is a prime.

It is a super-2 number, since 2×78595921081² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78595921181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39297960540 + 39297960541.

It is an arithmetic number, because the mean of its divisors is an integer number (39297960541).

Almost surely, 2^78595921081 is an apocalyptic number.

It is an amenable number.

78595921081 is a deficient number, since it is larger than the sum of its proper divisors (1).

78595921081 is an equidigital number, since it uses as much as digits as its factorization.

78595921081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1814400, while the sum is 55.

The spelling of 78595921081 in words is "seventy-eight billion, five hundred ninety-five million, nine hundred twenty-one thousand, eighty-one".