81893520 has 120 divisors (see below), whose sum is σ = 277857216. Its totient is φ = 21613824.

The previous prime is 81893507. The next prime is 81893521. The reversal of 81893520 is 2539818.

It is a tau number, because it is divible by the number of its divisors (120).

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

It is not an unprimeable number, because it can be changed into a prime (81893521) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 76509 + ... + 77571.

Almost surely, 2^81893520 is an apocalyptic number.

81893520 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 81893520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (138928608).

81893520 is an abundant number, since it is smaller than the sum of its proper divisors (195963696).

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

81893520 is a wasteful number, since it uses less digits than its factorization.

81893520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1189 (or 1180 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 81893520 is about 9049.5038538033. The cubic root of 81893520 is about 434.2600181835.

The spelling of 81893520 in words is "eighty-one million, eight hundred ninety-three thousand, five hundred twenty".