81253240 has 32 divisors (see below), whose sum is σ = 186274080. Its totient is φ = 31887232.

The previous prime is 81253231. The next prime is 81253247. The reversal of 81253240 is 4235218.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81253247) 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, 17044 + ... + 21283.

It is an arithmetic number, because the mean of its divisors is an integer number (5821065).

Almost surely, 2^81253240 is an apocalyptic number.

It is an amenable number.

81253240 is an abundant number, since it is smaller than the sum of its proper divisors (105020840).

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

81253240 is a wasteful number, since it uses less digits than its factorization.

81253240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38391 (or 38387 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 81253240 is about 9014.0579097319. The cubic root of 81253240 is about 433.1253097523.

Adding to 81253240 its reverse (4235218), we get a palindrome (85488458).

The spelling of 81253240 in words is "eighty-one million, two hundred fifty-three thousand, two hundred forty".