81939574 has 8 divisors (see below), whose sum is σ = 123023520. Its totient is φ = 40931736.

The previous prime is 81939569. The next prime is 81939601. The reversal of 81939574 is 47593918.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16254 + ... + 20689.

It is an arithmetic number, because the mean of its divisors is an integer number (15377940).

Almost surely, 2^81939574 is an apocalyptic number.

81939574 is a deficient number, since it is larger than the sum of its proper divisors (41083946).

81939574 is a wasteful number, since it uses less digits than its factorization.

81939574 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38054.

The product of its digits is 272160, while the sum is 46.

The square root of 81939574 is about 9052.0480555507. The cubic root of 81939574 is about 434.3414070531.

The spelling of 81939574 in words is "eighty-one million, nine hundred thirty-nine thousand, five hundred seventy-four".