81872340 has 96 divisors (see below), whose sum is σ = 264829824. Its totient is φ = 18677760.

The previous prime is 81872339. The next prime is 81872359. The reversal of 81872340 is 4327818.

It is a Harshad number since it is a multiple of its sum of digits (33).

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, 7572 + ... + 14868.

It is an arithmetic number, because the mean of its divisors is an integer number (2758644).

Almost surely, 2^81872340 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81872340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (132414912).

81872340 is an abundant number, since it is smaller than the sum of its proper divisors (182957484).

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

81872340 is a wasteful number, since it uses less digits than its factorization.

81872340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7337 (or 7335 counting only the distinct ones).

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

The square root of 81872340 is about 9048.3335482286. Note that the first 3 decimals coincide. The cubic root of 81872340 is about 434.2225776134. Note that the first 3 decimals are identical.

The spelling of 81872340 in words is "eighty-one million, eight hundred seventy-two thousand, three hundred forty".