81933609 has 4 divisors (see below), whose sum is σ = 109244816. Its totient is φ = 54622404.

The previous prime is 81933583. The next prime is 81933623. The reversal of 81933609 is 90633918.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 81933609 - 2⁹ = 81933097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81933629) 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, 13655599 + ... + 13655604.

It is an arithmetic number, because the mean of its divisors is an integer number (27311204).

Almost surely, 2^81933609 is an apocalyptic number.

It is an amenable number.

81933609 is a deficient number, since it is larger than the sum of its proper divisors (27311207).

81933609 is a wasteful number, since it uses less digits than its factorization.

81933609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27311206.

The product of its (nonzero) digits is 34992, while the sum is 39.

The square root of 81933609 is about 9051.7185661067. The cubic root of 81933609 is about 434.3308671343.

The spelling of 81933609 in words is "eighty-one million, nine hundred thirty-three thousand, six hundred nine".