31397213 has 2 divisors, whose sum is σ = 31397214. Its totient is φ = 31397212.

The previous prime is 31397209. The next prime is 31397221. The reversal of 31397213 is 31279313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 28922884 + 2474329 = 5378^2 + 1573^2 .

It is a cyclic number.

It is not a de Polignac number, because 31397213 - 2² = 31397209 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31397243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15698606 + 15698607.

It is an arithmetic number, because the mean of its divisors is an integer number (15698607).

Almost surely, 2^31397213 is an apocalyptic number.

It is an amenable number.

31397213 is a deficient number, since it is larger than the sum of its proper divisors (1).

31397213 is an equidigital number, since it uses as much as digits as its factorization.

31397213 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3402, while the sum is 29.

The square root of 31397213 is about 5603.3216041916. The cubic root of 31397213 is about 315.4740925228.

The spelling of 31397213 in words is "thirty-one million, three hundred ninety-seven thousand, two hundred thirteen".