81892720 has 120 divisors (see below), whose sum is σ = 238672224. Its totient is φ = 25901568.

The previous prime is 81892691. The next prime is 81892721. The reversal of 81892720 is 2729818.

It is a super-3 number, since 3×81892720³ (a number of 25 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81892720.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81892721) 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, 50157 + ... + 51763.

Almost surely, 2^81892720 is an apocalyptic number.

81892720 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 81892720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (119336112).

81892720 is an abundant number, since it is smaller than the sum of its proper divisors (156779504).

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

81892720 is a wasteful number, since it uses less digits than its factorization.

81892720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1647 (or 1634 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 81892720 is about 9049.4596523770. The cubic root of 81892720 is about 434.2586041150.

The spelling of 81892720 in words is "eighty-one million, eight hundred ninety-two thousand, seven hundred twenty".