81821952 has 108 divisors (see below), whose sum is σ = 249909660. Its totient is φ = 25657344.

The previous prime is 81821951. The next prime is 81821953. The reversal of 81821952 is 25912818.

It is an interprime number because it is at equal distance from previous prime (81821951) and next prime (81821953).

It can be written as a sum of positive squares in 2 ways, for example, as 68161536 + 13660416 = 8256^2 + 3696^2 .

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 (81821951) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 38124 + ... + 40212.

Almost surely, 2^81821952 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 81821952, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (124954830).

81821952 is an abundant number, since it is smaller than the sum of its proper divisors (168087708).

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

81821952 is a wasteful number, since it uses less digits than its factorization.

81821952 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2128 (or 2111 counting only the distinct ones).

The product of its digits is 11520, while the sum is 36.

The square root of 81821952 is about 9045.5487395735. The cubic root of 81821952 is about 434.1334791570.

The spelling of 81821952 in words is "eighty-one million, eight hundred twenty-one thousand, nine hundred fifty-two".