81490391 has 8 divisors (see below), whose sum is σ = 83876640. Its totient is φ = 79113888.

The previous prime is 81490369. The next prime is 81490393. The reversal of 81490391 is 19309418.

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

It is a cyclic number.

It is not a de Polignac number, because 81490391 - 2²⁶ = 14381527 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81490393) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16670 + ... + 20996.

It is an arithmetic number, because the mean of its divisors is an integer number (10484580).

Almost surely, 2^81490391 is an apocalyptic number.

81490391 is a deficient number, since it is larger than the sum of its proper divisors (2386249).

81490391 is a wasteful number, since it uses less digits than its factorization.

81490391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4873.

The product of its (nonzero) digits is 7776, while the sum is 35.

The square root of 81490391 is about 9027.2028336578. The cubic root of 81490391 is about 433.5462830401.

The spelling of 81490391 in words is "eighty-one million, four hundred ninety thousand, three hundred ninety-one".