79201981 has 4 divisors (see below), whose sum is σ = 80696412. Its totient is φ = 77707552.

The previous prime is 79201979. The next prime is 79202021. The reversal of 79201981 is 18910297.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18910297 = 7 ⋅2701471.

It can be written as a sum of positive squares in 2 ways, for example, as 60140025 + 19061956 = 7755^2 + 4366^2 .

It is a cyclic number.

It is not a de Polignac number, because 79201981 - 2¹ = 79201979 is a prime.

It is a super-2 number, since 2×79201981² = 12545907588648722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 79201981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (79201081) 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, 747136 + ... + 747241.

It is an arithmetic number, because the mean of its divisors is an integer number (20174103).

Almost surely, 2^79201981 is an apocalyptic number.

It is an amenable number.

79201981 is a deficient number, since it is larger than the sum of its proper divisors (1494431).

79201981 is a wasteful number, since it uses less digits than its factorization.

79201981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1494430.

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 79201981 is about 8899.5494829795. The cubic root of 79201981 is about 429.4494142966.

It can be divided in two parts, 792019 and 81, that added together give a square (792100 = 890²).

The spelling of 79201981 in words is "seventy-nine million, two hundred one thousand, nine hundred eighty-one".