80691991 has 2 divisors, whose sum is σ = 80691992. Its totient is φ = 80691990.

The previous prime is 80691983. The next prime is 80692049. The reversal of 80691991 is 19919608.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 80691991 - 2³ = 80691983 is a prime.

It is a super-2 number, since 2×80691991² = 13022394823088162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (80691901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40345995 + 40345996.

It is an arithmetic number, because the mean of its divisors is an integer number (40345996).

Almost surely, 2^80691991 is an apocalyptic number.

80691991 is a deficient number, since it is larger than the sum of its proper divisors (1).

80691991 is an equidigital number, since it uses as much as digits as its factorization.

80691991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34992, while the sum is 43.

The square root of 80691991 is about 8982.8720908182. The cubic root of 80691991 is about 432.1257475014.

The spelling of 80691991 in words is "eighty million, six hundred ninety-one thousand, nine hundred ninety-one".