80815981 has 2 divisors, whose sum is σ = 80815982. Its totient is φ = 80815980.

The previous prime is 80815921. The next prime is 80815991. The reversal of 80815981 is 18951808.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 56115081 + 24700900 = 7491^2 + 4970^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-80815981 is a prime.

It is a super-2 number, since 2×80815981² = 13062445569984722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (80815921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40407990 + 40407991.

It is an arithmetic number, because the mean of its divisors is an integer number (40407991).

Almost surely, 2^80815981 is an apocalyptic number.

It is an amenable number.

80815981 is a deficient number, since it is larger than the sum of its proper divisors (1).

80815981 is an equidigital number, since it uses as much as digits as its factorization.

80815981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23040, while the sum is 40.

The square root of 80815981 is about 8989.7709092056. The cubic root of 80815981 is about 432.3469666962.

It can be divided in two parts, 80815 and 981, that added together give a square (81796 = 286²).

The spelling of 80815981 in words is "eighty million, eight hundred fifteen thousand, nine hundred eighty-one".