31123661 has 2 divisors, whose sum is σ = 31123662. Its totient is φ = 31123660.

The previous prime is 31123649. The next prime is 31123679. The reversal of 31123661 is 16632113.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25694761 + 5428900 = 5069^2 + 2330^2 .

It is an emirp because it is prime and its reverse (16632113) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31123661 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31123601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15561830 + 15561831.

It is an arithmetic number, because the mean of its divisors is an integer number (15561831).

Almost surely, 2^31123661 is an apocalyptic number.

It is an amenable number.

31123661 is a deficient number, since it is larger than the sum of its proper divisors (1).

31123661 is an equidigital number, since it uses as much as digits as its factorization.

31123661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 648, while the sum is 23.

The square root of 31123661 is about 5578.8583957652. The cubic root of 31123661 is about 314.5552167182. Note that the first 3 decimals are identical.

Adding to 31123661 its reverse (16632113), we get a palindrome (47755774).

The spelling of 31123661 in words is "thirty-one million, one hundred twenty-three thousand, six hundred sixty-one".