81938490 has 32 divisors (see below), whose sum is σ = 197527680. Its totient is φ = 21753024.

The previous prime is 81938429. The next prime is 81938491. The reversal of 81938490 is 9483918.

It is a super-2 number, since 2×81938490² = 13427832286960200, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81938491) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 907 + ... + 12833.

It is an arithmetic number, because the mean of its divisors is an integer number (6172740).

Almost surely, 2^81938490 is an apocalyptic number.

81938490 is an abundant number, since it is smaller than the sum of its proper divisors (115589190).

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

81938490 is a wasteful number, since it uses less digits than its factorization.

81938490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12166.

The product of its (nonzero) digits is 62208, while the sum is 42.

The square root of 81938490 is about 9051.9881794001. The cubic root of 81938490 is about 434.3394917061.

It can be divided in two parts, 81938 and 490, that added together give a palindrome (82428).

The spelling of 81938490 in words is "eighty-one million, nine hundred thirty-eight thousand, four hundred ninety".