81994380 has 96 divisors (see below), whose sum is σ = 255295488. Its totient is φ = 19526400.

The previous prime is 81994373. The next prime is 81994387. The reversal of 81994380 is 8349918.

It is an interprime number because it is at equal distance from previous prime (81994373) and next prime (81994387).

It is not an unprimeable number, because it can be changed into a prime (81994387) 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 31 ways as a sum of consecutive naturals, for example, 22485 + ... + 25875.

It is an arithmetic number, because the mean of its divisors is an integer number (2659328).

Almost surely, 2^81994380 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 81994380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (127647744).

81994380 is an abundant number, since it is smaller than the sum of its proper divisors (173301108).

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

81994380 is a wasteful number, since it uses less digits than its factorization.

81994380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3447 (or 3445 counting only the distinct ones).

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

The square root of 81994380 is about 9055.0748202320. The cubic root of 81994380 is about 434.4382231526.

The spelling of 81994380 in words is "eighty-one million, nine hundred ninety-four thousand, three hundred eighty".