81894459 has 4 divisors (see below), whose sum is σ = 109192616. Its totient is φ = 54596304.

The previous prime is 81894443. The next prime is 81894493. The reversal of 81894459 is 95449818.

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

It is not a de Polignac number, because 81894459 - 2⁴ = 81894443 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81894499) 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, 13649074 + ... + 13649079.

It is an arithmetic number, because the mean of its divisors is an integer number (27298154).

Almost surely, 2^81894459 is an apocalyptic number.

81894459 is a deficient number, since it is larger than the sum of its proper divisors (27298157).

81894459 is a wasteful number, since it uses less digits than its factorization.

81894459 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27298156.

The product of its digits is 414720, while the sum is 48.

The square root of 81894459 is about 9049.5557349519. Note that the first 3 decimals coincide. The cubic root of 81894459 is about 434.2616779347.

The spelling of 81894459 in words is "eighty-one million, eight hundred ninety-four thousand, four hundred fifty-nine".