81914581 has 4 divisors (see below), whose sum is σ = 93616672. Its totient is φ = 70212492.

The previous prime is 81914563. The next prime is 81914587. The reversal of 81914581 is 18541918.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 81914581 - 2⁵ = 81914549 is a prime.

It is a super-2 number, since 2×81914581² = 13419997160811122, which contains 22 as substring.

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 81914581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81914587) 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, 5851035 + ... + 5851048.

It is an arithmetic number, because the mean of its divisors is an integer number (23404168).

Almost surely, 2^81914581 is an apocalyptic number.

It is an amenable number.

81914581 is a deficient number, since it is larger than the sum of its proper divisors (11702091).

81914581 is a wasteful number, since it uses less digits than its factorization.

81914581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11702090.

The product of its digits is 11520, while the sum is 37.

The square root of 81914581 is about 9050.6674339520. The cubic root of 81914581 is about 434.2972419928.

It can be divided in two parts, 819 and 14581, that added together give a triangular number (15400 = T₁₇₅).

The spelling of 81914581 in words is "eighty-one million, nine hundred fourteen thousand, five hundred eighty-one".