81749360 has 160 divisors (see below), whose sum is σ = 247698432. Its totient is φ = 24330240.

The previous prime is 81749357. The next prime is 81749377. The reversal of 81749360 is 6394718.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 141392 + ... + 141968.

Almost surely, 2^81749360 is an apocalyptic number.

81749360 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 81749360, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123849216).

81749360 is an abundant number, since it is smaller than the sum of its proper divisors (165949072).

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

81749360 is a wasteful number, since it uses less digits than its factorization.

81749360 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 631 (or 625 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 38.

The square root of 81749360 is about 9041.5352678624. The cubic root of 81749360 is about 434.0050542001.

The spelling of 81749360 in words is "eighty-one million, seven hundred forty-nine thousand, three hundred sixty".