78725657 has 4 divisors (see below), whose sum is σ = 83356596. Its totient is φ = 74094720.

The previous prime is 78725653. The next prime is 78725663. The reversal of 78725657 is 75652787.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 23609881 + 55115776 = 4859^2 + 7424^2 .

It is a cyclic number.

It is not a de Polignac number, because 78725657 - 2² = 78725653 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78725653) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2315444 + ... + 2315477.

It is an arithmetic number, because the mean of its divisors is an integer number (20839149).

Almost surely, 2^78725657 is an apocalyptic number.

It is an amenable number.

78725657 is a deficient number, since it is larger than the sum of its proper divisors (4630939).

78725657 is a wasteful number, since it uses less digits than its factorization.

78725657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4630938.

The product of its digits is 823200, while the sum is 47.

The square root of 78725657 is about 8872.7479959706. The cubic root of 78725657 is about 428.5867737945.

The spelling of 78725657 in words is "seventy-eight million, seven hundred twenty-five thousand, six hundred fifty-seven".