81642582 has 96 divisors (see below), whose sum is σ = 216403200. Its totient is φ = 21726144.

The previous prime is 81642581. The next prime is 81642599. The reversal of 81642582 is 28524618.

81642582 is a `hidden beast` number, since 8 + 1 + 642 + 5 + 8 + 2 = 666.

It is a super-2 number, since 2×81642582² = 13331022391253448, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81642581) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 160144 + ... + 160652.

It is an arithmetic number, because the mean of its divisors is an integer number (2254200).

Almost surely, 2^81642582 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81642582, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108201600).

81642582 is an abundant number, since it is smaller than the sum of its proper divisors (134760618).

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

81642582 is a wasteful number, since it uses less digits than its factorization.

81642582 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 610 (or 607 counting only the distinct ones).

The product of its digits is 30720, while the sum is 36.

The square root of 81642582 is about 9035.6284784181. The cubic root of 81642582 is about 433.8160114025.

The spelling of 81642582 in words is "eighty-one million, six hundred forty-two thousand, five hundred eighty-two".