81582940 has 24 divisors (see below), whose sum is σ = 171510192. Its totient is φ = 32597760.

The previous prime is 81582937. The next prime is 81582947. The reversal of 81582940 is 4928518.

It is a self number, because there is not a number n which added to its sum of digits gives 81582940.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81582947) 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, 24580 + ... + 27700.

It is an arithmetic number, because the mean of its divisors is an integer number (7146258).

Almost surely, 2^81582940 is an apocalyptic number.

It is an amenable number.

81582940 is an abundant number, since it is smaller than the sum of its proper divisors (89927252).

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

81582940 is a wasteful number, since it uses less digits than its factorization.

81582940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4437 (or 4435 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 37.

The square root of 81582940 is about 9032.3274962769. The cubic root of 81582940 is about 433.7103477609.

The spelling of 81582940 in words is "eighty-one million, five hundred eighty-two thousand, nine hundred forty".