80720991 has 36 divisors (see below), whose sum is σ = 128161488. Its totient is φ = 48926592.

The previous prime is 80720963. The next prime is 80720999. The reversal of 80720991 is 19902708.

It is a happy number.

It is not a de Polignac number, because 80720991 - 2¹⁷ = 80589919 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (80720999) 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 35 ways as a sum of consecutive naturals, for example, 110670 + ... + 111396.

Almost surely, 2^80720991 is an apocalyptic number.

80720991 is a deficient number, since it is larger than the sum of its proper divisors (47440497).

80720991 is a wasteful number, since it uses less digits than its factorization.

80720991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 832 (or 816 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 80720991 is about 8984.4861288779. The cubic root of 80720991 is about 432.1775087132.

The spelling of 80720991 in words is "eighty million, seven hundred twenty thousand, nine hundred ninety-one".