81537750 has 192 divisors, whose sum is σ = 261660672. Its totient is φ = 17928000.

The previous prime is 81537707. The next prime is 81537767. The reversal of 81537750 is 5773518.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 488167 + ... + 488333.

It is an arithmetic number, because the mean of its divisors is an integer number (1362816).

Almost surely, 2^81537750 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81537750, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130830336).

81537750 is an abundant number, since it is smaller than the sum of its proper divisors (180122922).

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

81537750 is a wasteful number, since it uses less digits than its factorization.

81537750 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228 (or 215 counting only the distinct ones).

The product of its (nonzero) digits is 29400, while the sum is 36.

The square root of 81537750 is about 9029.8255797108. The cubic root of 81537750 is about 433.6302534400.

The spelling of 81537750 in words is "eighty-one million, five hundred thirty-seven thousand, seven hundred fifty".