81535899 has 4 divisors (see below), whose sum is σ = 108714536. Its totient is φ = 54357264.

The previous prime is 81535879. The next prime is 81535931. The reversal of 81535899 is 99853518.

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

It is not a de Polignac number, because 81535899 - 2⁷ = 81535771 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81535829) 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, 13589314 + ... + 13589319.

It is an arithmetic number, because the mean of its divisors is an integer number (27178634).

Almost surely, 2^81535899 is an apocalyptic number.

81535899 is a deficient number, since it is larger than the sum of its proper divisors (27178637).

81535899 is a wasteful number, since it uses less digits than its factorization.

81535899 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27178636.

The product of its digits is 388800, while the sum is 48.

The square root of 81535899 is about 9029.7230854551. The cubic root of 81535899 is about 433.6269721146.

The spelling of 81535899 in words is "eighty-one million, five hundred thirty-five thousand, eight hundred ninety-nine".