80899991 has 4 divisors (see below), whose sum is σ = 85658832. Its totient is φ = 76141152.

The previous prime is 80899981. The next prime is 80899999. The reversal of 80899991 is 19999808.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-80899991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (80899999) 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, 2379395 + ... + 2379428.

It is an arithmetic number, because the mean of its divisors is an integer number (21414708).

Almost surely, 2^80899991 is an apocalyptic number.

80899991 is a deficient number, since it is larger than the sum of its proper divisors (4758841).

80899991 is a wasteful number, since it uses less digits than its factorization.

80899991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4758840.

The product of its (nonzero) digits is 419904, while the sum is 53.

The square root of 80899991 is about 8994.4422283986. The cubic root of 80899991 is about 432.4967262273.

The spelling of 80899991 in words is "eighty million, eight hundred ninety-nine thousand, nine hundred ninety-one".