81861516 has 120 divisors (see below), whose sum is σ = 236780544. Its totient is φ = 24455520.

The previous prime is 81861487. The next prime is 81861517. The reversal of 81861516 is 61516818.

81861516 is a `hidden beast` number, since 81 + 8 + 61 + 516 = 666.

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 (81861517) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 366981 + ... + 367203.

Almost surely, 2^81861516 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 81861516, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118390272).

81861516 is an abundant number, since it is smaller than the sum of its proper divisors (154919028).

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

81861516 is a wasteful number, since it uses less digits than its factorization.

81861516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 353 (or 342 counting only the distinct ones).

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

The square root of 81861516 is about 9047.7354072718. The cubic root of 81861516 is about 434.2034411858.

The spelling of 81861516 in words is "eighty-one million, eight hundred sixty-one thousand, five hundred sixteen".