79720121 has 4 divisors (see below), whose sum is σ = 85852452. Its totient is φ = 73587792.

The previous prime is 79720117. The next prime is 79720211. The reversal of 79720121 is 12102797.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12102797 = 7 ⋅1728971.

It can be written as a sum of positive squares in 2 ways, for example, as 31764496 + 47955625 = 5636^2 + 6925^2 .

It is a cyclic number.

It is not a de Polignac number, because 79720121 - 2² = 79720117 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (79720721) 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, 3066146 + ... + 3066171.

It is an arithmetic number, because the mean of its divisors is an integer number (21463113).

Almost surely, 2^79720121 is an apocalyptic number.

It is an amenable number.

79720121 is a deficient number, since it is larger than the sum of its proper divisors (6132331).

79720121 is a wasteful number, since it uses less digits than its factorization.

79720121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6132330.

The product of its (nonzero) digits is 1764, while the sum is 29.

The square root of 79720121 is about 8928.6124901913. The cubic root of 79720121 is about 430.3838666977.

The spelling of 79720121 in words is "seventy-nine million, seven hundred twenty thousand, one hundred twenty-one".