81993499 has 8 divisors (see below), whose sum is σ = 99219168. Its totient is φ = 66145920.

The previous prime is 81993487. The next prime is 81993503. The reversal of 81993499 is 99439918.

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 81993499 - 2⁷ = 81993371 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81993409) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 344392 + ... + 344629.

It is an arithmetic number, because the mean of its divisors is an integer number (12402396).

Almost surely, 2^81993499 is an apocalyptic number.

81993499 is a deficient number, since it is larger than the sum of its proper divisors (17225669).

81993499 is a wasteful number, since it uses less digits than its factorization.

81993499 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 689045.

The product of its digits is 629856, while the sum is 52.

The square root of 81993499 is about 9055.0261733470. The cubic root of 81993499 is about 434.4366671864.

The spelling of 81993499 in words is "eighty-one million, nine hundred ninety-three thousand, four hundred ninety-nine".