31189021 has 2 divisors, whose sum is σ = 31189022. Its totient is φ = 31189020.

The previous prime is 31189019. The next prime is 31189049. The reversal of 31189021 is 12098113.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 24108100 + 7080921 = 4910^2 + 2661^2 .

It is an emirp because it is prime and its reverse (12098113) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31189021 - 2¹ = 31189019 is a prime.

Together with 31189019, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31189091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15594510 + 15594511.

It is an arithmetic number, because the mean of its divisors is an integer number (15594511).

Almost surely, 2^31189021 is an apocalyptic number.

It is an amenable number.

31189021 is a deficient number, since it is larger than the sum of its proper divisors (1).

31189021 is an equidigital number, since it uses as much as digits as its factorization.

31189021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 31189021 is about 5584.7131528844. The cubic root of 31189021 is about 314.7752524667.

The spelling of 31189021 in words is "thirty-one million, one hundred eighty-nine thousand, twenty-one".