81259940 has 24 divisors (see below), whose sum is σ = 170835000. Its totient is φ = 32467968.

The previous prime is 81259931. The next prime is 81259957. The reversal of 81259940 is 4995218.

It can be written as a sum of positive squares in 4 ways, for example, as 28494244 + 52765696 = 5338^2 + 7264^2 .

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 81259894 and 81259903.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23354 + ... + 26606.

It is an arithmetic number, because the mean of its divisors is an integer number (7118125).

Almost surely, 2^81259940 is an apocalyptic number.

It is an amenable number.

81259940 is an abundant number, since it is smaller than the sum of its proper divisors (89575060).

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

81259940 is a wasteful number, since it uses less digits than its factorization.

81259940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4511 (or 4509 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 38.

The square root of 81259940 is about 9014.4295437926. The cubic root of 81259940 is about 433.1372143435.

The spelling of 81259940 in words is "eighty-one million, two hundred fifty-nine thousand, nine hundred forty".