81356856 has 64 divisors (see below), whose sum is σ = 237216000. Its totient is φ = 23242464.

The previous prime is 81356851. The next prime is 81356887. The reversal of 81356856 is 65865318.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81356851) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3291 + ... + 13173.

It is an arithmetic number, because the mean of its divisors is an integer number (3706500).

Almost surely, 2^81356856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81356856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118608000).

81356856 is an abundant number, since it is smaller than the sum of its proper divisors (155859144).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81356856 is a wasteful number, since it uses less digits than its factorization.

81356856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9913 (or 9895 counting only the distinct ones).

The product of its digits is 172800, while the sum is 42.

The square root of 81356856 is about 9019.8035455325. The cubic root of 81356856 is about 433.3093419985.

The spelling of 81356856 in words is "eighty-one million, three hundred fifty-six thousand, eight hundred fifty-six".