81507857 has 8 divisors (see below), whose sum is σ = 82344192. Its totient is φ = 80676000.

The previous prime is 81507847. The next prime is 81507863. The reversal of 81507857 is 75870518.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81507857 - 2¹² = 81503761 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81507817) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44357 + ... + 46157.

It is an arithmetic number, because the mean of its divisors is an integer number (10293024).

Almost surely, 2^81507857 is an apocalyptic number.

It is an amenable number.

81507857 is a deficient number, since it is larger than the sum of its proper divisors (836335).

81507857 is a wasteful number, since it uses less digits than its factorization.

81507857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2239.

The product of its (nonzero) digits is 78400, while the sum is 41.

The square root of 81507857 is about 9028.1701911295. The cubic root of 81507857 is about 433.5772551107.

The spelling of 81507857 in words is "eighty-one million, five hundred seven thousand, eight hundred fifty-seven".