81863712 has 108 divisors (see below), whose sum is σ = 270854766. Its totient is φ = 23385600.

The previous prime is 81863711. The next prime is 81863741. The reversal of 81863712 is 21736818.

81863712 is a `hidden beast` number, since 8 + 1 + 8 + 637 + 12 = 666.

It can be written as a sum of positive squares in only one way, i.e., 46294416 + 35569296 = 6804^2 + 5964^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (81863711) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 11212 + ... + 17012.

Almost surely, 2^81863712 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 81863712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (135427383).

81863712 is an abundant number, since it is smaller than the sum of its proper divisors (188991054).

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

81863712 is a wasteful number, since it uses less digits than its factorization.

81863712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5831 (or 5813 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 81863712 is about 9047.8567627919. The cubic root of 81863712 is about 434.2073237682.

The spelling of 81863712 in words is "eighty-one million, eight hundred sixty-three thousand, seven hundred twelve".