31109621 has 2 divisors, whose sum is σ = 31109622. Its totient is φ = 31109620.

The previous prime is 31109599. The next prime is 31109623. The reversal of 31109621 is 12690113.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 30924721 + 184900 = 5561^2 + 430^2 .

It is an emirp because it is prime and its reverse (12690113) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31109621 - 2⁶ = 31109557 is a prime.

Together with 31109623, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31109623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15554810 + 15554811.

It is an arithmetic number, because the mean of its divisors is an integer number (15554811).

Almost surely, 2^31109621 is an apocalyptic number.

It is an amenable number.

31109621 is a deficient number, since it is larger than the sum of its proper divisors (1).

31109621 is an equidigital number, since it uses as much as digits as its factorization.

31109621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 324, while the sum is 23.

The square root of 31109621 is about 5577.5999318703. The cubic root of 31109621 is about 314.5079105922.

Adding to 31109621 its reverse (12690113), we get a palindrome (43799734).

The spelling of 31109621 in words is "thirty-one million, one hundred nine thousand, six hundred twenty-one".