78971861 has 4 divisors (see below), whose sum is σ = 79093452. Its totient is φ = 78850272.

The previous prime is 78971831. The next prime is 78971873. The reversal of 78971861 is 16817987.

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 47679025 + 31292836 = 6905^2 + 5594^2 .

It is a cyclic number.

It is not a de Polignac number, because 78971861 - 2¹⁴ = 78955477 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 (78971831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 59816 + ... + 61121.

It is an arithmetic number, because the mean of its divisors is an integer number (19773363).

Almost surely, 2^78971861 is an apocalyptic number.

It is an amenable number.

78971861 is a deficient number, since it is larger than the sum of its proper divisors (121591).

78971861 is a wasteful number, since it uses less digits than its factorization.

78971861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121590.

The product of its digits is 169344, while the sum is 47.

The square root of 78971861 is about 8886.6113339113. The cubic root of 78971861 is about 429.0330915224.

The spelling of 78971861 in words is "seventy-eight million, nine hundred seventy-one thousand, eight hundred sixty-one".