81733440 has 112 divisors (see below), whose sum is σ = 273222720. Its totient is φ = 20643840.

The previous prime is 81733439. The next prime is 81733441. The reversal of 81733440 is 4433718.

It is an interprime number because it is at equal distance from previous prime (81733439) and next prime (81733441).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 81733398 and 81733407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81733441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16000 + ... + 20480.

Almost surely, 2^81733440 is an apocalyptic number.

81733440 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 81733440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (136611360).

81733440 is an abundant number, since it is smaller than the sum of its proper divisors (191489280).

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

81733440 is a wasteful number, since it uses less digits than its factorization.

81733440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4520 (or 4510 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 30.

The square root of 81733440 is about 9040.6548435387. The cubic root of 81733440 is about 433.9768794269.

The spelling of 81733440 in words is "eighty-one million, seven hundred thirty-three thousand, four hundred forty".