31123021 has 2 divisors, whose sum is σ = 31123022. Its totient is φ = 31123020.

The previous prime is 31123019. The next prime is 31123067. The reversal of 31123021 is 12032113.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19900521 + 11222500 = 4461^2 + 3350^2 .

It is a cyclic number.

It is not a de Polignac number, because 31123021 - 2¹ = 31123019 is a prime.

Together with 31123019, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 31122992 and 31123010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31121021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15561510 + 15561511.

It is an arithmetic number, because the mean of its divisors is an integer number (15561511).

Almost surely, 2^31123021 is an apocalyptic number.

It is an amenable number.

31123021 is a deficient number, since it is larger than the sum of its proper divisors (1).

31123021 is an equidigital number, since it uses as much as digits as its factorization.

31123021 is an odious number, because the sum of its binary digits is odd.

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

The square root of 31123021 is about 5578.8010360650. The cubic root of 31123021 is about 314.5530606231.

Adding to 31123021 its reverse (12032113), we get a palindrome (43155134).

It can be divided in two parts, 311 and 23021, that added together give a palindrome (23332).

The spelling of 31123021 in words is "thirty-one million, one hundred twenty-three thousand, twenty-one".