81901859 has 4 divisors (see below), whose sum is σ = 88202016. Its totient is φ = 75601704.

The previous prime is 81901849. The next prime is 81901861. The reversal of 81901859 is 95810918.

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 81901859 - 2⁴ = 81901843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81901849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3150059 + ... + 3150084.

It is an arithmetic number, because the mean of its divisors is an integer number (22050504).

Almost surely, 2^81901859 is an apocalyptic number.

81901859 is a deficient number, since it is larger than the sum of its proper divisors (6300157).

81901859 is a wasteful number, since it uses less digits than its factorization.

81901859 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6300156.

The product of its (nonzero) digits is 25920, while the sum is 41.

The square root of 81901859 is about 9049.9645855661. The cubic root of 81901859 is about 434.2747575319.

The spelling of 81901859 in words is "eighty-one million, nine hundred one thousand, eight hundred fifty-nine".