81894645 has 48 divisors (see below), whose sum is σ = 168255360. Its totient is φ = 37433664.

The previous prime is 81894641. The next prime is 81894647. The reversal of 81894645 is 54649818.

81894645 is a `hidden beast` number, since 8 + 189 + 464 + 5 = 666.

It is not a de Polignac number, because 81894645 - 2² = 81894641 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 81894645.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81894641) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3691 + ... + 13319.

It is an arithmetic number, because the mean of its divisors is an integer number (3505320).

Almost surely, 2^81894645 is an apocalyptic number.

It is an amenable number.

81894645 is an abundant number, since it is smaller than the sum of its proper divisors (86360715).

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

81894645 is an equidigital number, since it uses as much as digits as its factorization.

81894645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9656 (or 9644 counting only the distinct ones).

The product of its digits is 276480, while the sum is 45.

The square root of 81894645 is about 9049.5660116936. The cubic root of 81894645 is about 434.2620067018.

The spelling of 81894645 in words is "eighty-one million, eight hundred ninety-four thousand, six hundred forty-five".