81900420 has 96 divisors (see below), whose sum is σ = 264633600. Its totient is φ = 18537984.

The previous prime is 81900409. The next prime is 81900439. The reversal of 81900420 is 2400918.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 44886 + ... + 46674.

It is an arithmetic number, because the mean of its divisors is an integer number (2756600).

Almost surely, 2^81900420 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81900420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (132316800).

81900420 is an abundant number, since it is smaller than the sum of its proper divisors (182733180).

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

81900420 is a wasteful number, since it uses less digits than its factorization.

81900420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1917 (or 1915 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 81900420 is about 9049.8850821433. The cubic root of 81900420 is about 434.2722141422.

The spelling of 81900420 in words is "eighty-one million, nine hundred thousand, four hundred twenty".