31223513 has 2 divisors, whose sum is σ = 31223514. Its totient is φ = 31223512.

The previous prime is 31223503. The next prime is 31223531. The reversal of 31223513 is 31532213.

Together with next prime (31223531) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27175369 + 4048144 = 5213^2 + 2012^2 .

It is a cyclic number.

It is not a de Polignac number, because 31223513 - 2⁴ = 31223497 is a prime.

It is a super-2 number, since 2×31223513² = 1949815528122338, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (31223503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15611756 + 15611757.

It is an arithmetic number, because the mean of its divisors is an integer number (15611757).

Almost surely, 2^31223513 is an apocalyptic number.

It is an amenable number.

31223513 is a deficient number, since it is larger than the sum of its proper divisors (1).

31223513 is an equidigital number, since it uses as much as digits as its factorization.

31223513 is an evil number, because the sum of its binary digits is even.

The product of its digits is 540, while the sum is 20.

The square root of 31223513 is about 5587.8003722395. The cubic root of 31223513 is about 314.8912465759.

Adding to 31223513 its reverse (31532213), we get a palindrome (62755726).

It can be divided in two parts, 3122 and 3513, that multiplied together give a triangular number (10967586 = T₄₆₈₃).

The spelling of 31223513 in words is "thirty-one million, two hundred twenty-three thousand, five hundred thirteen".