31000313221 has 4 divisors (see below), whose sum is σ = 31007592844. Its totient is φ = 30993033600.

The previous prime is 31000313207. The next prime is 31000313243. The reversal of 31000313221 is 12231300013.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12231300013 = 22271 ⋅549203.

It can be written as a sum of positive squares in 2 ways, for example, as 22086120996 + 8914192225 = 148614^2 + 94415^2 .

It is a cyclic number.

It is not a de Polignac number, because 31000313221 - 2¹⁷ = 31000182149 is a prime.

It is a super-2 number, since 2×31000313221² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31000313195 and 31000313204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31000313021) 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, 3633420 + ... + 3641941.

It is an arithmetic number, because the mean of its divisors is an integer number (7751898211).

Almost surely, 2^31000313221 is an apocalyptic number.

It is an amenable number.

31000313221 is a deficient number, since it is larger than the sum of its proper divisors (7279623).

31000313221 is an equidigital number, since it uses as much as digits as its factorization.

31000313221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7279622.

The product of its (nonzero) digits is 108, while the sum is 16.

Adding to 31000313221 its reverse (12231300013), we get a palindrome (43231613234).

The spelling of 31000313221 in words is "thirty-one billion, three hundred thirteen thousand, two hundred twenty-one".