31121789 has 4 divisors (see below), whose sum is σ = 31407420. Its totient is φ = 30836160.

The previous prime is 31121777. The next prime is 31121803. The reversal of 31121789 is 98712113.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14784025 + 16337764 = 3845^2 + 4042^2 .

It is a cyclic number.

It is not a de Polignac number, because 31121789 - 2¹⁶ = 31056253 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31121719) 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, 142652 + ... + 142869.

It is an arithmetic number, because the mean of its divisors is an integer number (7851855).

Almost surely, 2^31121789 is an apocalyptic number.

It is an amenable number.

31121789 is a deficient number, since it is larger than the sum of its proper divisors (285631).

31121789 is a wasteful number, since it uses less digits than its factorization.

31121789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 285630.

The product of its digits is 3024, while the sum is 32.

The square root of 31121789 is about 5578.6906169817. The cubic root of 31121789 is about 314.5489100568.

The spelling of 31121789 in words is "thirty-one million, one hundred twenty-one thousand, seven hundred eighty-nine".