81937659 has 4 divisors (see below), whose sum is σ = 109250216. Its totient is φ = 54625104.

The previous prime is 81937657. The next prime is 81937729. The reversal of 81937659 is 95673918.

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

It is not a de Polignac number, because 81937659 - 2¹ = 81937657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81937651) 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, 13656274 + ... + 13656279.

It is an arithmetic number, because the mean of its divisors is an integer number (27312554).

Almost surely, 2^81937659 is an apocalyptic number.

81937659 is a deficient number, since it is larger than the sum of its proper divisors (27312557).

81937659 is a wasteful number, since it uses less digits than its factorization.

81937659 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27312556.

The product of its digits is 408240, while the sum is 48.

The square root of 81937659 is about 9051.9422777656. The cubic root of 81937659 is about 434.3380233797.

The spelling of 81937659 in words is "eighty-one million, nine hundred thirty-seven thousand, six hundred fifty-nine".