81752440 has 192 divisors, whose sum is σ = 245145600. Its totient is φ = 23950080.

The previous prime is 81752431. The next prime is 81752443. The reversal of 81752440 is 4425718.

It is a super-2 number, since 2×81752440² = 13366922891907200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81752443) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 643657 + ... + 643783.

It is an arithmetic number, because the mean of its divisors is an integer number (1276800).

Almost surely, 2^81752440 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 81752440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (122572800).

81752440 is an abundant number, since it is smaller than the sum of its proper divisors (163393160).

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

81752440 is a wasteful number, since it uses less digits than its factorization.

81752440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186 (or 171 counting only the distinct ones).

The product of its (nonzero) digits is 8960, while the sum is 31.

The square root of 81752440 is about 9041.7055913141. The cubic root of 81752440 is about 434.0105046761.

The spelling of 81752440 in words is "eighty-one million, seven hundred fifty-two thousand, four hundred forty".