81232021 has 16 divisors (see below), whose sum is σ = 91719936. Its totient is φ = 71381376.

The previous prime is 81232003. The next prime is 81232033. The reversal of 81232021 is 12023218.

It is a cyclic number.

It is not a de Polignac number, because 81232021 - 2⁹ = 81231509 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81232021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81232091) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 78121 + ... + 79153.

It is an arithmetic number, because the mean of its divisors is an integer number (5732496).

Almost surely, 2^81232021 is an apocalyptic number.

It is an amenable number.

81232021 is a deficient number, since it is larger than the sum of its proper divisors (10487915).

81232021 is a wasteful number, since it uses less digits than its factorization.

81232021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1332.

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 81232021 is about 9012.8808380007. The cubic root of 81232021 is about 433.0876034156.

Adding to 81232021 its reverse (12023218), we get a palindrome (93255239).

The spelling of 81232021 in words is "eighty-one million, two hundred thirty-two thousand, twenty-one".