31123861 has 2 divisors, whose sum is σ = 31123862. Its totient is φ = 31123860.

The previous prime is 31123817. The next prime is 31123871. The reversal of 31123861 is 16832113.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 22033636 + 9090225 = 4694^2 + 3015^2 .

It is a cyclic number.

It is not a de Polignac number, because 31123861 - 2¹⁷ = 30992789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31123811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15561930 + 15561931.

It is an arithmetic number, because the mean of its divisors is an integer number (15561931).

Almost surely, 2^31123861 is an apocalyptic number.

It is an amenable number.

31123861 is a deficient number, since it is larger than the sum of its proper divisors (1).

31123861 is an equidigital number, since it uses as much as digits as its factorization.

31123861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 864, while the sum is 25.

The square root of 31123861 is about 5578.8763205506. The cubic root of 31123861 is about 314.5558904919. Note that the first 3 decimals are identical.

Adding to 31123861 its reverse (16832113), we get a palindrome (47955974).

The spelling of 31123861 in words is "thirty-one million, one hundred twenty-three thousand, eight hundred sixty-one".