81858164 has 6 divisors (see below), whose sum is σ = 143251794. Its totient is φ = 40929080.

The previous prime is 81858163. The next prime is 81858167. The reversal of 81858164 is 46185818.

It can be written as a sum of positive squares in only one way, i.e., 51696100 + 30162064 = 7190^2 + 5492^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81858163) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10232267 + ... + 10232274.

It is an arithmetic number, because the mean of its divisors is an integer number (23875299).

Almost surely, 2^81858164 is an apocalyptic number.

It is an amenable number.

81858164 is a deficient number, since it is larger than the sum of its proper divisors (61393630).

81858164 is a wasteful number, since it uses less digits than its factorization.

81858164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20464545 (or 20464543 counting only the distinct ones).

The product of its digits is 61440, while the sum is 41.

The square root of 81858164 is about 9047.5501656526. The cubic root of 81858164 is about 434.1975146330.

The spelling of 81858164 in words is "eighty-one million, eight hundred fifty-eight thousand, one hundred sixty-four".