81669159 has 96 divisors (see below), whose sum is σ = 150958080. Its totient is φ = 41817600.

The previous prime is 81669151. The next prime is 81669187. The reversal of 81669159 is 95196618.

It is not a de Polignac number, because 81669159 - 2³ = 81669151 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81669151) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 917587 + ... + 917675.

It is an arithmetic number, because the mean of its divisors is an integer number (1572480).

Almost surely, 2^81669159 is an apocalyptic number.

81669159 is a gapful number since it is divisible by the number (89) formed by its first and last digit.

81669159 is a deficient number, since it is larger than the sum of its proper divisors (69288921).

81669159 is a wasteful number, since it uses less digits than its factorization.

81669159 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173 (or 170 counting only the distinct ones).

The product of its digits is 116640, while the sum is 45.

The square root of 81669159 is about 9037.0990367485. The cubic root of 81669159 is about 433.8630794766.

The spelling of 81669159 in words is "eighty-one million, six hundred sixty-nine thousand, one hundred fifty-nine".