81504499 has 4 divisors (see below), whose sum is σ = 81525960. Its totient is φ = 81483040.

The previous prime is 81504491. The next prime is 81504503. The reversal of 81504499 is 99440518.

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 81504499 - 2³ = 81504491 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 (81504491) 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, 3334 + ... + 13195.

It is an arithmetic number, because the mean of its divisors is an integer number (20381490).

Almost surely, 2^81504499 is an apocalyptic number.

81504499 is a deficient number, since it is larger than the sum of its proper divisors (21461).

81504499 is a wasteful number, since it uses less digits than its factorization.

81504499 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21460.

The product of its (nonzero) digits is 51840, while the sum is 40.

The square root of 81504499 is about 9027.9842157594. The cubic root of 81504499 is about 433.5713007873.

The spelling of 81504499 in words is "eighty-one million, five hundred four thousand, four hundred ninety-nine".