31131213109 has 2 divisors, whose sum is σ = 31131213110. Its totient is φ = 31131213108.

The previous prime is 31131213107. The next prime is 31131213149. The reversal of 31131213109 is 90131213113.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 28729233009 + 2401980100 = 169497^2 + 49010^2 .

It is an emirp because it is prime and its reverse (90131213113) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31131213109 - 2¹ = 31131213107 is a prime.

Together with 31131213107, 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 (31131213107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15565606554 + 15565606555.

It is an arithmetic number, because the mean of its divisors is an integer number (15565606555).

Almost surely, 2^31131213109 is an apocalyptic number.

It is an amenable number.

31131213109 is a deficient number, since it is larger than the sum of its proper divisors (1).

31131213109 is an equidigital number, since it uses as much as digits as its factorization.

31131213109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 486, while the sum is 25.

The spelling of 31131213109 in words is "thirty-one billion, one hundred thirty-one million, two hundred thirteen thousand, one hundred nine".