80616721 has 4 divisors (see below), whose sum is σ = 80634852. Its totient is φ = 80598592.

The previous prime is 80616713. The next prime is 80616733. The reversal of 80616721 is 12761608.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10660225 + 69956496 = 3265^2 + 8364^2 .

It is a cyclic number.

It is not a de Polignac number, because 80616721 - 2³ = 80616713 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (80616751) 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, 2661 + ... + 12973.

It is an arithmetic number, because the mean of its divisors is an integer number (20158713).

Almost surely, 2^80616721 is an apocalyptic number.

It is an amenable number.

80616721 is a deficient number, since it is larger than the sum of its proper divisors (18131).

80616721 is a wasteful number, since it uses less digits than its factorization.

80616721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18130.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 80616721 is about 8978.6814733568. The cubic root of 80616721 is about 431.9913424905.

The spelling of 80616721 in words is "eighty million, six hundred sixteen thousand, seven hundred twenty-one".