81814861 has 4 divisors (see below), whose sum is σ = 81833724. Its totient is φ = 81796000.

The previous prime is 81814801. The next prime is 81814867. The reversal of 81814861 is 16841818.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 77105961 + 4708900 = 8781^2 + 2170^2 .

It is a cyclic number.

It is not a de Polignac number, because 81814861 - 2¹⁵ = 81782093 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81814861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81814867) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 711 + ... + 12811.

It is an arithmetic number, because the mean of its divisors is an integer number (20458431).

Almost surely, 2^81814861 is an apocalyptic number.

It is an amenable number.

81814861 is a deficient number, since it is larger than the sum of its proper divisors (18863).

81814861 is a wasteful number, since it uses less digits than its factorization.

81814861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18862.

The product of its digits is 12288, while the sum is 37.

The square root of 81814861 is about 9045.1567703385. The cubic root of 81814861 is about 434.1209375780.

The spelling of 81814861 in words is "eighty-one million, eight hundred fourteen thousand, eight hundred sixty-one".