80815921 has 2 divisors, whose sum is σ = 80815922. Its totient is φ = 80815920.

The previous prime is 80815919. The next prime is 80815981. The reversal of 80815921 is 12951808.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77704225 + 3111696 = 8815^2 + 1764^2 .

It is a cyclic number.

It is not a de Polignac number, because 80815921 - 2¹ = 80815919 is a prime.

Together with 80815919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (80815981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40407960 + 40407961.

It is an arithmetic number, because the mean of its divisors is an integer number (40407961).

Almost surely, 2^80815921 is an apocalyptic number.

It is an amenable number.

80815921 is a deficient number, since it is larger than the sum of its proper divisors (1).

80815921 is an equidigital number, since it uses as much as digits as its factorization.

80815921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5760, while the sum is 34.

The square root of 80815921 is about 8989.7675720788. The cubic root of 80815921 is about 432.3468597007.

The spelling of 80815921 in words is "eighty million, eight hundred fifteen thousand, nine hundred twenty-one".