81491760 has 480 divisors, whose sum is σ = 352834560. Its totient is φ = 16422912.

The previous prime is 81491759. The next prime is 81491771. The reversal of 81491760 is 6719418.

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 2202462 + ... + 2202498.

It is an arithmetic number, because the mean of its divisors is an integer number (735072).

Almost surely, 2^81491760 is an apocalyptic number.

81491760 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81491760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (176417280).

81491760 is an abundant number, since it is smaller than the sum of its proper divisors (271342800).

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

81491760 is a wasteful number, since it uses less digits than its factorization.

81491760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105 (or 96 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 36.

The square root of 81491760 is about 9027.2786597069. The cubic root of 81491760 is about 433.5487108173.

The spelling of 81491760 in words is "eighty-one million, four hundred ninety-one thousand, seven hundred sixty".