78815761 has 2 divisors, whose sum is σ = 78815762. Its totient is φ = 78815760.

The previous prime is 78815753. The next prime is 78815771. The reversal of 78815761 is 16751887.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69205761 + 9610000 = 8319^2 + 3100^2 .

It is a cyclic number.

It is not a de Polignac number, because 78815761 - 2³ = 78815753 is a prime.

It is not a weakly prime, because it can be changed into another prime (78815771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39407880 + 39407881.

It is an arithmetic number, because the mean of its divisors is an integer number (39407881).

Almost surely, 2^78815761 is an apocalyptic number.

It is an amenable number.

78815761 is a deficient number, since it is larger than the sum of its proper divisors (1).

78815761 is an equidigital number, since it uses as much as digits as its factorization.

78815761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 94080, while the sum is 43.

The square root of 78815761 is about 8877.8241140496. The cubic root of 78815761 is about 428.7502218179.

The spelling of 78815761 in words is "seventy-eight million, eight hundred fifteen thousand, seven hundred sixty-one".