31072861 has 4 divisors (see below), whose sum is σ = 31095324. Its totient is φ = 31050400.

The previous prime is 31072849. The next prime is 31072879. The reversal of 31072861 is 16827013.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16827013 = 7 ⋅2403859.

It can be written as a sum of positive squares in 2 ways, for example, as 14516100 + 16556761 = 3810^2 + 4069^2 .

It is a cyclic number.

It is not a de Polignac number, because 31072861 - 2¹⁷ = 30941789 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 (31072831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9010 + ... + 11971.

It is an arithmetic number, because the mean of its divisors is an integer number (7773831).

Almost surely, 2^31072861 is an apocalyptic number.

It is an amenable number.

31072861 is a deficient number, since it is larger than the sum of its proper divisors (22463).

31072861 is a wasteful number, since it uses less digits than its factorization.

31072861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22462.

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 31072861 is about 5574.3036336389. The cubic root of 31072861 is about 314.3839846476.

Adding to 31072861 its reverse (16827013), we get a palindrome (47899874).

The spelling of 31072861 in words is "thirty-one million, seventy-two thousand, eight hundred sixty-one".