31821081437 has 2 divisors, whose sum is σ = 31821081438. Its totient is φ = 31821081436.

The previous prime is 31821081433. The next prime is 31821081521. The reversal of 31821081437 is 73418012813.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25734897241 + 6086184196 = 160421^2 + 78014^2 .

It is a cyclic number.

It is not a de Polignac number, because 31821081437 - 2² = 31821081433 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31821081437.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31821081431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15910540718 + 15910540719.

It is an arithmetic number, because the mean of its divisors is an integer number (15910540719).

Almost surely, 2^31821081437 is an apocalyptic number.

It is an amenable number.

31821081437 is a deficient number, since it is larger than the sum of its proper divisors (1).

31821081437 is an equidigital number, since it uses as much as digits as its factorization.

31821081437 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32256, while the sum is 38.

The spelling of 31821081437 in words is "thirty-one billion, eight hundred twenty-one million, eighty-one thousand, four hundred thirty-seven".