31123513 has 2 divisors, whose sum is σ = 31123514. Its totient is φ = 31123512.

The previous prime is 31123511. The next prime is 31123559. The reversal of 31123513 is 31532113.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21930489 + 9193024 = 4683^2 + 3032^2 .

It is an emirp because it is prime and its reverse (31532113) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31123513 - 2¹ = 31123511 is a prime.

It is a super-2 number, since 2×31123513² = 1937346122922338, which contains 22 as substring.

Together with 31123511, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (31123511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15561756 + 15561757.

It is an arithmetic number, because the mean of its divisors is an integer number (15561757).

Almost surely, 2^31123513 is an apocalyptic number.

It is an amenable number.

31123513 is a deficient number, since it is larger than the sum of its proper divisors (1).

31123513 is an equidigital number, since it uses as much as digits as its factorization.

31123513 is an evil number, because the sum of its binary digits is even.

The product of its digits is 270, while the sum is 19.

The square root of 31123513 is about 5578.8451313870. The cubic root of 31123513 is about 314.5547181238.

Adding to 31123513 its reverse (31532113), we get a palindrome (62655626).

The spelling of 31123513 in words is "thirty-one million, one hundred twenty-three thousand, five hundred thirteen".