81998727 has 4 divisors (see below), whose sum is σ = 109331640. Its totient is φ = 54665816.

The previous prime is 81998671. The next prime is 81998743. The reversal of 81998727 is 72789918.

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

It is a cyclic number.

It is not a de Polignac number, because 81998727 - 2²⁰ = 80950151 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81998727.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81998767) 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, 13666452 + ... + 13666457.

It is an arithmetic number, because the mean of its divisors is an integer number (27332910).

Almost surely, 2^81998727 is an apocalyptic number.

81998727 is a deficient number, since it is larger than the sum of its proper divisors (27332913).

81998727 is a wasteful number, since it uses less digits than its factorization.

81998727 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27332912.

The product of its digits is 508032, while the sum is 51.

The square root of 81998727 is about 9055.3148481983. The cubic root of 81998727 is about 434.4459003844.

The spelling of 81998727 in words is "eighty-one million, nine hundred ninety-eight thousand, seven hundred twenty-seven".