81872420 has 48 divisors (see below), whose sum is σ = 199210368. Its totient is φ = 27682560.

The previous prime is 81872419. The next prime is 81872429. The reversal of 81872420 is 2427818.

It is not an unprimeable number, because it can be changed into a prime (81872429) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6215 + ... + 14225.

It is an arithmetic number, because the mean of its divisors is an integer number (4150216).

Almost surely, 2^81872420 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 81872420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (99605184).

81872420 is an abundant number, since it is smaller than the sum of its proper divisors (117337948).

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

81872420 is a wasteful number, since it uses less digits than its factorization.

81872420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8100 (or 8098 counting only the distinct ones).

The product of its (nonzero) digits is 7168, while the sum is 32.

The square root of 81872420 is about 9048.3379689311. The cubic root of 81872420 is about 434.2227190442. Note that the first 3 decimals are identical.

The spelling of 81872420 in words is "eighty-one million, eight hundred seventy-two thousand, four hundred twenty".