81775806 has 24 divisors (see below), whose sum is σ = 190254600. Its totient is φ = 23364432.

The previous prime is 81775801. The next prime is 81775871. The reversal of 81775806 is 60857718.

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 (81775801) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 138781 + ... + 139368.

It is an arithmetic number, because the mean of its divisors is an integer number (7927275).

Almost surely, 2^81775806 is an apocalyptic number.

81775806 is an abundant number, since it is smaller than the sum of its proper divisors (108478794).

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

81775806 is a wasteful number, since it uses less digits than its factorization.

81775806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 278168 (or 278161 counting only the distinct ones).

The product of its (nonzero) digits is 94080, while the sum is 42.

The square root of 81775806 is about 9042.9976224701. The cubic root of 81775806 is about 434.0518495112.

The spelling of 81775806 in words is "eighty-one million, seven hundred seventy-five thousand, eight hundred six".