81994940 has 24 divisors (see below), whose sum is σ = 172585392. Its totient is φ = 32722560.

The previous prime is 81994933. The next prime is 81994943. The reversal of 81994940 is 4949918.

It is a junction number, because it is equal to n+sod(n) for n = 81994891 and 81994900.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81994943) 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 7 ways as a sum of consecutive naturals, for example, 4655 + ... + 13625.

It is an arithmetic number, because the mean of its divisors is an integer number (7191058).

Almost surely, 2^81994940 is an apocalyptic number.

It is an amenable number.

81994940 is an abundant number, since it is smaller than the sum of its proper divisors (90590452).

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

81994940 is a wasteful number, since it uses less digits than its factorization.

81994940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9437 (or 9435 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 44.

The square root of 81994940 is about 9055.1057420662. The cubic root of 81994940 is about 434.4392121832.

It can be divided in two parts, 819 and 94940, that added together give a palindrome (95759).

The spelling of 81994940 in words is "eighty-one million, nine hundred ninety-four thousand, nine hundred forty".