81880915 has 4 divisors (see below), whose sum is σ = 98257104. Its totient is φ = 65504728.

The previous prime is 81880913. The next prime is 81880921. The reversal of 81880915 is 51908818.

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

It is a cyclic number.

It is not a de Polignac number, because 81880915 - 2¹ = 81880913 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81880913) 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, 8188087 + ... + 8188096.

It is an arithmetic number, because the mean of its divisors is an integer number (24564276).

Almost surely, 2^81880915 is an apocalyptic number.

81880915 is a deficient number, since it is larger than the sum of its proper divisors (16376189).

81880915 is a wasteful number, since it uses less digits than its factorization.

81880915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16376188.

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

The square root of 81880915 is about 9048.8073799811. The cubic root of 81880915 is about 434.2377366957.

The spelling of 81880915 in words is "eighty-one million, eight hundred eighty thousand, nine hundred fifteen".