81881394 has 16 divisors (see below), whose sum is σ = 187157568. Its totient is φ = 23394672.

The previous prime is 81881383. The next prime is 81881441. The reversal of 81881394 is 49318818.

It is a Harshad number since it is a multiple of its sum of digits (42), and also a Moran number because the ratio is a prime number: 1949557 = 81881394 / (8 + 1 + 8 + 8 + 1 + 3 + 9 + 4).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 974737 + ... + 974820.

It is an arithmetic number, because the mean of its divisors is an integer number (11697348).

Almost surely, 2^81881394 is an apocalyptic number.

81881394 is an abundant number, since it is smaller than the sum of its proper divisors (105276174).

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

81881394 is a wasteful number, since it uses less digits than its factorization.

81881394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1949569.

The product of its digits is 55296, while the sum is 42.

The square root of 81881394 is about 9048.8338475187. The cubic root of 81881394 is about 434.2385834517.

The spelling of 81881394 in words is "eighty-one million, eight hundred eighty-one thousand, three hundred ninety-four".