31001213 has 4 divisors (see below), whose sum is σ = 31014780. Its totient is φ = 30987648.

The previous prime is 31001161. The next prime is 31001221. The reversal of 31001213 is 31210013.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31210013 = 3137 ⋅9949.

It can be written as a sum of positive squares in 2 ways, for example, as 13344409 + 17656804 = 3653^2 + 4202^2 .

It is a cyclic number.

It is not a de Polignac number, because 31001213 - 2¹⁸ = 30739069 is a prime.

It is a super-2 number, since 2×31001213² = 1922150414942738, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 31001194 and 31001203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31001233) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2420 + ... + 8237.

It is an arithmetic number, because the mean of its divisors is an integer number (7753695).

Almost surely, 2^31001213 is an apocalyptic number.

It is an amenable number.

31001213 is a deficient number, since it is larger than the sum of its proper divisors (13567).

31001213 is a wasteful number, since it uses less digits than its factorization.

31001213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13566.

The product of its (nonzero) digits is 18, while the sum is 11.

The square root of 31001213 is about 5567.8732923801. The cubic root of 31001213 is about 314.1421624919.

Adding to 31001213 its reverse (31210013), we get a palindrome (62211226).

The spelling of 31001213 in words is "thirty-one million, one thousand, two hundred thirteen".