81556998 has 16 divisors (see below), whose sum is σ = 165879360. Its totient is φ = 26724776.

The previous prime is 81556967. The next prime is 81557009. The reversal of 81556998 is 89965518.

It is a self number, because there is not a number n which added to its sum of digits gives 81556998.

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 7 ways as a sum of consecutive naturals, for example, 114840 + ... + 115547.

It is an arithmetic number, because the mean of its divisors is an integer number (10367460).

Almost surely, 2^81556998 is an apocalyptic number.

81556998 is an abundant number, since it is smaller than the sum of its proper divisors (84322362).

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

81556998 is a wasteful number, since it uses less digits than its factorization.

81556998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 230451.

The product of its digits is 777600, while the sum is 51.

The square root of 81556998 is about 9030.8913181369. The cubic root of 81556998 is about 433.6643720270.

The spelling of 81556998 in words is "eighty-one million, five hundred fifty-six thousand, nine hundred ninety-eight".