81551824 has 20 divisors (see below), whose sum is σ = 163104640. Its totient is φ = 39460320.

The previous prime is 81551801. The next prime is 81551831. The reversal of 81551824 is 42815518.

81551824 is an admirable number.

It is a self number, because there is not a number n which added to its sum of digits gives 81551824.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 81714 + ... + 82705.

It is an arithmetic number, because the mean of its divisors is an integer number (8155232).

Almost surely, 2^81551824 is an apocalyptic number.

It is an amenable number.

81551824 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

81551824 is a wasteful number, since it uses less digits than its factorization.

81551824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164458 (or 164452 counting only the distinct ones).

The product of its digits is 12800, while the sum is 34.

The square root of 81551824 is about 9030.6048523895. The cubic root of 81551824 is about 433.6552012345.

The spelling of 81551824 in words is "eighty-one million, five hundred fifty-one thousand, eight hundred twenty-four".