79661981 has 8 divisors (see below), whose sum is σ = 91552320. Its totient is φ = 67899168.

The previous prime is 79661963. The next prime is 79661987. The reversal of 79661981 is 18916697.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 79661981 - 2⁶ = 79661917 is a prime.

It is a super-2 number, since 2×79661981² = 12692062433688722, 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 (79661987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30536 + ... + 33041.

It is an arithmetic number, because the mean of its divisors is an integer number (11444040).

Almost surely, 2^79661981 is an apocalyptic number.

It is an amenable number.

79661981 is a deficient number, since it is larger than the sum of its proper divisors (11890339).

79661981 is a wasteful number, since it uses less digits than its factorization.

79661981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63763.

The product of its digits is 163296, while the sum is 47.

The square root of 79661981 is about 8925.3560713285. The cubic root of 79661981 is about 430.2792147264.

The spelling of 79661981 in words is "seventy-nine million, six hundred sixty-one thousand, nine hundred eighty-one".