81985534 has 4 divisors (see below), whose sum is σ = 122978304. Its totient is φ = 40992766.

The previous prime is 81985529. The next prime is 81985559. The reversal of 81985534 is 43558918.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20496382 + ... + 20496385.

It is an arithmetic number, because the mean of its divisors is an integer number (30744576).

Almost surely, 2^81985534 is an apocalyptic number.

81985534 is a deficient number, since it is larger than the sum of its proper divisors (40992770).

81985534 is a wasteful number, since it uses less digits than its factorization.

81985534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40992769.

The product of its digits is 172800, while the sum is 43.

The square root of 81985534 is about 9054.5863516784. The cubic root of 81985534 is about 434.4225994040.

The spelling of 81985534 in words is "eighty-one million, nine hundred eighty-five thousand, five hundred thirty-four".