81901900 has 36 divisors (see below), whose sum is σ = 178278520. Its totient is φ = 32659200.

The previous prime is 81901889. The next prime is 81901909. The reversal of 81901900 is 910918.

It is a super-2 number, since 2×81901900² = 13415842447220000, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81901909) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 36820 + ... + 38980.

Almost surely, 2^81901900 is an apocalyptic number.

It is an amenable number.

81901900 is an abundant number, since it is smaller than the sum of its proper divisors (96376620).

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

81901900 is a wasteful number, since it uses less digits than its factorization.

81901900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2554 (or 2547 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 28.

The square root of 81901900 is about 9049.9668507680. The cubic root of 81901900 is about 434.2748299978.

The spelling of 81901900 in words is "eighty-one million, nine hundred one thousand, nine hundred".