81909898 has 16 divisors (see below), whose sum is σ = 140607360. Its totient is φ = 35056656.

The previous prime is 81909887. The next prime is 81909899. The reversal of 81909898 is 89890918.

It is not an unprimeable number, because it can be changed into a prime (81909899) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7968 + ... + 15076.

It is an arithmetic number, because the mean of its divisors is an integer number (8787960).

Almost surely, 2^81909898 is an apocalyptic number.

81909898 is a deficient number, since it is larger than the sum of its proper divisors (58697462).

81909898 is a wasteful number, since it uses less digits than its factorization.

81909898 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7941.

The product of its (nonzero) digits is 373248, while the sum is 52.

The square root of 81909898 is about 9050.4087200524. The cubic root of 81909898 is about 434.2889656773.

The spelling of 81909898 in words is "eighty-one million, nine hundred nine thousand, eight hundred ninety-eight".