31221013 has 8 divisors (see below), whose sum is σ = 31577400. Its totient is φ = 30866880.

The previous prime is 31220989. The next prime is 31221017. The reversal of 31221013 is 31012213.

It can be written as a sum of positive squares in 4 ways, for example, as 106929 + 31114084 = 327^2 + 5578^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 31221013 - 2¹⁷ = 31089941 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31220984 and 31221002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31221017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 46903 + ... + 47563.

It is an arithmetic number, because the mean of its divisors is an integer number (3947175).

Almost surely, 2^31221013 is an apocalyptic number.

It is an amenable number.

31221013 is a deficient number, since it is larger than the sum of its proper divisors (356387).

31221013 is a wasteful number, since it uses less digits than its factorization.

31221013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1127.

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 31221013 is about 5587.5766661407. The cubic root of 31221013 is about 314.8828421284.

Adding to 31221013 its reverse (31012213), we get a palindrome (62233226).

The spelling of 31221013 in words is "thirty-one million, two hundred twenty-one thousand, thirteen".