81165770 has 32 divisors (see below), whose sum is σ = 167280768. Its totient is φ = 27776448.

The previous prime is 81165767. The next prime is 81165779. The reversal of 81165770 is 7756118.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81165770.

It is not an unprimeable number, because it can be changed into a prime (81165779) 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, 69209 + ... + 70371.

It is an arithmetic number, because the mean of its divisors is an integer number (5227524).

Almost surely, 2^81165770 is an apocalyptic number.

81165770 is an abundant number, since it is smaller than the sum of its proper divisors (86114998).

81165770 is a wasteful number, since it uses less digits than its factorization.

81165770 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2174.

The product of its (nonzero) digits is 11760, while the sum is 35.

The square root of 81165770 is about 9009.2047373783. The cubic root of 81165770 is about 432.9698325730.

The spelling of 81165770 in words is "eighty-one million, one hundred sixty-five thousand, seven hundred seventy".