81641584 has 10 divisors (see below), whose sum is σ = 158180600. Its totient is φ = 40820784.

The previous prime is 81641561. The next prime is 81641587. The reversal of 81641584 is 48514618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81641587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2551284 + ... + 2551315.

It is an arithmetic number, because the mean of its divisors is an integer number (15818060).

Almost surely, 2^81641584 is an apocalyptic number.

It is an amenable number.

81641584 is a deficient number, since it is larger than the sum of its proper divisors (76539016).

81641584 is a wasteful number, since it uses less digits than its factorization.

81641584 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5102607 (or 5102601 counting only the distinct ones).

The product of its digits is 30720, while the sum is 37.

The square root of 81641584 is about 9035.5732524284. The cubic root of 81641584 is about 433.8142437377.

The spelling of 81641584 in words is "eighty-one million, six hundred forty-one thousand, five hundred eighty-four".