79859781 has 6 divisors (see below), whose sum is σ = 115353030. Its totient is φ = 53239848.

The previous prime is 79859723. The next prime is 79859783. The reversal of 79859781 is 18795897.

It can be written as a sum of positive squares in only one way, i.e., 54154881 + 25704900 = 7359^2 + 5070^2 .

It is not a de Polignac number, because 79859781 - 2¹¹ = 79857733 is a prime.

It is a super-2 number, since 2×79859781² = 12755169242735922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (79859783) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4436646 + ... + 4436663.

It is an arithmetic number, because the mean of its divisors is an integer number (19225505).

Almost surely, 2^79859781 is an apocalyptic number.

It is an amenable number.

79859781 is a deficient number, since it is larger than the sum of its proper divisors (35493249).

79859781 is a wasteful number, since it uses less digits than its factorization.

79859781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8873315 (or 8873312 counting only the distinct ones).

The product of its digits is 1270080, while the sum is 54.

The square root of 79859781 is about 8936.4299918927. The cubic root of 79859781 is about 430.6350468845.

It can be divided in two parts, 7985 and 9781, that added together give a triangular number (17766 = T₁₈₈).

The spelling of 79859781 in words is "seventy-nine million, eight hundred fifty-nine thousand, seven hundred eighty-one".