79966981 has 4 divisors (see below), whose sum is σ = 79985952. Its totient is φ = 79948012.

The previous prime is 79966973. The next prime is 79966987. The reversal of 79966981 is 18966997.

79966981 is a nontrivial binomial coefficient, being equal to C(12647, 2).

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.

It is not a de Polignac number, because 79966981 - 2³ = 79966973 is a prime.

It is a super-2 number, since 2×79966981² = 12789436100508722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (79966987) 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, 1 + ... + 12646.

It is an arithmetic number, because the mean of its divisors is an integer number (19996488).

Almost surely, 2^79966981 is an apocalyptic number.

79966981 is the 12646-th triangular number.

79966981 is the 4216-th centered nonagonal number.

It is an amenable number.

79966981 is a deficient number, since it is larger than the sum of its proper divisors (18971).

79966981 is a wasteful number, since it uses less digits than its factorization.

79966981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18970.

The product of its digits is 1469664, while the sum is 55.

The square root of 79966981 is about 8942.4259012865. The cubic root of 79966981 is about 430.8276487828.

The spelling of 79966981 in words is "seventy-nine million, nine hundred sixty-six thousand, nine hundred eighty-one".