81990115 has 8 divisors (see below), whose sum is σ = 98472528. Its totient is φ = 65535840.

The previous prime is 81990107. The next prime is 81990143. The reversal of 81990115 is 51109918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81990115 - 2³ = 81990107 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25 + ... + 12805.

It is an arithmetic number, because the mean of its divisors is an integer number (12309066).

Almost surely, 2^81990115 is an apocalyptic number.

81990115 is a deficient number, since it is larger than the sum of its proper divisors (16482413).

81990115 is a wasteful number, since it uses less digits than its factorization.

81990115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14069.

The product of its (nonzero) digits is 3240, while the sum is 34.

The square root of 81990115 is about 9054.8393138697. The cubic root of 81990115 is about 434.4306904772.

The spelling of 81990115 in words is "eighty-one million, nine hundred ninety thousand, one hundred fifteen".