81772428 has 96 divisors (see below), whose sum is σ = 209744640. Its totient is φ = 24710400.

The previous prime is 81772393. The next prime is 81772463. The reversal of 81772428 is 82427718.

It is an interprime number because it is at equal distance from previous prime (81772393) and next prime (81772463).

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, 809578 + ... + 809678.

It is an arithmetic number, because the mean of its divisors is an integer number (2184840).

Almost surely, 2^81772428 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 81772428, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104872320).

81772428 is an abundant number, since it is smaller than the sum of its proper divisors (127972212).

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

81772428 is a wasteful number, since it uses less digits than its factorization.

81772428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 247 (or 245 counting only the distinct ones).

The product of its digits is 50176, while the sum is 39.

The square root of 81772428 is about 9042.8108461916. The cubic root of 81772428 is about 434.0458728155.

The spelling of 81772428 in words is "eighty-one million, seven hundred seventy-two thousand, four hundred twenty-eight".