81890000 has 100 divisors (see below), whose sum is σ = 209183040. Its totient is φ = 30960000.

The previous prime is 81889993. The next prime is 81890021. The reversal of 81890000 is 9818.

It is a tau number, because it is divible by the number of its divisors (100).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 189785 + ... + 190215.

Almost surely, 2^81890000 is an apocalyptic number.

81890000 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81890000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104591520).

81890000 is an abundant number, since it is smaller than the sum of its proper divisors (127293040).

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

81890000 is a wasteful number, since it uses less digits than its factorization.

81890000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 478 (or 457 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 26.

The square root of 81890000 is about 9049.3093659130. The cubic root of 81890000 is about 434.2537962131.

Adding to 81890000 its reverse (9818), we get a palindrome (81899818).

The spelling of 81890000 in words is "eighty-one million, eight hundred ninety thousand".