78499477561 has 2 divisors, whose sum is σ = 78499477562. Its totient is φ = 78499477560.

The previous prime is 78499477547. The next prime is 78499477591. The reversal of 78499477561 is 16577499487.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77030671936 + 1468805625 = 277544^2 + 38325^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78499477561 is a prime.

It is not a weakly prime, because it can be changed into another prime (78499477591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39249738780 + 39249738781.

It is an arithmetic number, because the mean of its divisors is an integer number (39249738781).

Almost surely, 2^78499477561 is an apocalyptic number.

It is an amenable number.

78499477561 is a deficient number, since it is larger than the sum of its proper divisors (1).

78499477561 is an equidigital number, since it uses as much as digits as its factorization.

78499477561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 106686720, while the sum is 67.

The spelling of 78499477561 in words is "seventy-eight billion, four hundred ninety-nine million, four hundred seventy-seven thousand, five hundred sixty-one".