78686957 has 4 divisors (see below), whose sum is σ = 79795296. Its totient is φ = 77578620.

The previous prime is 78686941. The next prime is 78686963. The reversal of 78686957 is 75968687.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 75968687 = 67 ⋅1133861.

It is a cyclic number.

It is not a de Polignac number, because 78686957 - 2⁴ = 78686941 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78686357) 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, 554063 + ... + 554204.

It is an arithmetic number, because the mean of its divisors is an integer number (19948824).

Almost surely, 2^78686957 is an apocalyptic number.

It is an amenable number.

78686957 is a deficient number, since it is larger than the sum of its proper divisors (1108339).

78686957 is a wasteful number, since it uses less digits than its factorization.

78686957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1108338.

The product of its digits is 5080320, while the sum is 56.

The square root of 78686957 is about 8870.5668928203. The cubic root of 78686957 is about 428.5165339796.

The spelling of 78686957 in words is "seventy-eight million, six hundred eighty-six thousand, nine hundred fifty-seven".