31821089 has 4 divisors (see below), whose sum is σ = 31832724. Its totient is φ = 31809456.

The previous prime is 31821071. The next prime is 31821103. The reversal of 31821089 is 98012813.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 98012813 = 47 ⋅2085379.

It can be written as a sum of positive squares in 2 ways, for example, as 18190225 + 13630864 = 4265^2 + 3692^2 .

It is a cyclic number.

It is not a de Polignac number, because 31821089 - 2¹⁶ = 31755553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31821389) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 779 + ... + 8015.

It is an arithmetic number, because the mean of its divisors is an integer number (7958181).

Almost surely, 2^31821089 is an apocalyptic number.

It is an amenable number.

31821089 is a deficient number, since it is larger than the sum of its proper divisors (11635).

31821089 is an equidigital number, since it uses as much as digits as its factorization.

31821089 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11634.

The product of its (nonzero) digits is 3456, while the sum is 32.

The square root of 31821089 is about 5641.0184364173. The cubic root of 31821089 is about 316.8874303005.

The spelling of 31821089 in words is "thirty-one million, eight hundred twenty-one thousand, eighty-nine".