81440594 has 4 divisors (see below), whose sum is σ = 122160894. Its totient is φ = 40720296.

The previous prime is 81440573. The next prime is 81440617. The reversal of 81440594 is 49504418.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 41434969 + 40005625 = 6437^2 + 6325^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20360147 + ... + 20360150.

Almost surely, 2^81440594 is an apocalyptic number.

81440594 is a deficient number, since it is larger than the sum of its proper divisors (40720300).

81440594 is a wasteful number, since it uses less digits than its factorization.

81440594 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40720299.

The product of its (nonzero) digits is 23040, while the sum is 35.

The square root of 81440594 is about 9024.4442488167. Note that the first 3 decimals coincide. The cubic root of 81440594 is about 433.4579548210.

The spelling of 81440594 in words is "eighty-one million, four hundred forty thousand, five hundred ninety-four".