81959857 has 4 divisors (see below), whose sum is σ = 93668416. Its totient is φ = 70251300.

The previous prime is 81959837. The next prime is 81959897. The reversal of 81959857 is 75895918.

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 81959857 - 2⁷ = 81959729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81959837) 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, 5854269 + ... + 5854282.

It is an arithmetic number, because the mean of its divisors is an integer number (23417104).

Almost surely, 2^81959857 is an apocalyptic number.

It is an amenable number.

81959857 is a deficient number, since it is larger than the sum of its proper divisors (11708559).

81959857 is a wasteful number, since it uses less digits than its factorization.

81959857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11708558.

The product of its digits is 907200, while the sum is 52.

The square root of 81959857 is about 9053.1683404209. The cubic root of 81959857 is about 434.3772424845.

The spelling of 81959857 in words is "eighty-one million, nine hundred fifty-nine thousand, eight hundred fifty-seven".