81237321 has 24 divisors (see below), whose sum is σ = 128650080. Its totient is φ = 48988800.

The previous prime is 81237319. The next prime is 81237341. The reversal of 81237321 is 12373218.

It is not a de Polignac number, because 81237321 - 2¹ = 81237319 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81237341) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18945 + ... + 22833.

It is an arithmetic number, because the mean of its divisors is an integer number (5360420).

Almost surely, 2^81237321 is an apocalyptic number.

It is an amenable number.

81237321 is a deficient number, since it is larger than the sum of its proper divisors (47412759).

81237321 is a wasteful number, since it uses less digits than its factorization.

81237321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4117 (or 4114 counting only the distinct ones).

The product of its digits is 2016, while the sum is 27.

The square root of 81237321 is about 9013.1748568415. The cubic root of 81237321 is about 433.0970221741.

The spelling of 81237321 in words is "eighty-one million, two hundred thirty-seven thousand, three hundred twenty-one".