78692561 has 2 divisors, whose sum is σ = 78692562. Its totient is φ = 78692560.

The previous prime is 78692557. The next prime is 78692567. The reversal of 78692561 is 16529687.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 76457536 + 2235025 = 8744^2 + 1495^2 .

It is a cyclic number.

It is not a de Polignac number, because 78692561 - 2² = 78692557 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (78692567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39346280 + 39346281.

It is an arithmetic number, because the mean of its divisors is an integer number (39346281).

Almost surely, 2^78692561 is an apocalyptic number.

It is an amenable number.

78692561 is a deficient number, since it is larger than the sum of its proper divisors (1).

78692561 is an equidigital number, since it uses as much as digits as its factorization.

78692561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 181440, while the sum is 44.

The square root of 78692561 is about 8870.8827632880. The cubic root of 78692561 is about 428.5267065662.

The spelling of 78692561 in words is "seventy-eight million, six hundred ninety-two thousand, five hundred sixty-one".