81738240 has 160 divisors (see below), whose sum is σ = 271054080. Its totient is φ = 20987904.

The previous prime is 81738233. The next prime is 81738281. The reversal of 81738240 is 4283718.

81738240 is nontrivially palindromic in base 14.

It is a tau number, because it is divible by the number of its divisors (160).

It is a super-2 number, since 2×81738240² = 13362279756595200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 222537 + ... + 222903.

It is an arithmetic number, because the mean of its divisors is an integer number (1694088).

Almost surely, 2^81738240 is an apocalyptic number.

81738240 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 81738240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (135527040).

81738240 is an abundant number, since it is smaller than the sum of its proper divisors (189315840).

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

81738240 is a wasteful number, since it uses less digits than its factorization.

81738240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 422 (or 406 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 33.

The square root of 81738240 is about 9040.9203071369. The cubic root of 81738240 is about 433.9853747186.

The spelling of 81738240 in words is "eighty-one million, seven hundred thirty-eight thousand, two hundred forty".