81901938 has 16 divisors (see below), whose sum is σ = 169088256. Its totient is φ = 26419920.

The previous prime is 81901931. The next prime is 81901961. The reversal of 81901938 is 83910918.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 81901896 and 81901905.

It is not an unprimeable number, because it can be changed into a prime (81901931) 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, 219981 + ... + 220352.

It is an arithmetic number, because the mean of its divisors is an integer number (10568016).

Almost surely, 2^81901938 is an apocalyptic number.

81901938 is an abundant number, since it is smaller than the sum of its proper divisors (87186318).

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

81901938 is a wasteful number, since it uses less digits than its factorization.

81901938 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 440369.

The product of its (nonzero) digits is 15552, while the sum is 39.

The square root of 81901938 is about 9049.9689502230. The cubic root of 81901938 is about 434.2748971612.

The spelling of 81901938 in words is "eighty-one million, nine hundred one thousand, nine hundred thirty-eight".