31378491857 has 2 divisors, whose sum is σ = 31378491858. Its totient is φ = 31378491856.

The previous prime is 31378491847. The next prime is 31378491883. The reversal of 31378491857 is 75819487313.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25256837776 + 6121654081 = 158924^2 + 78241^2 .

It is a cyclic number.

It is not a de Polignac number, because 31378491857 - 2⁸ = 31378491601 is a prime.

It is not a weakly prime, because it can be changed into another prime (31378491817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15689245928 + 15689245929.

It is an arithmetic number, because the mean of its divisors is an integer number (15689245929).

Almost surely, 2^31378491857 is an apocalyptic number.

It is an amenable number.

31378491857 is a deficient number, since it is larger than the sum of its proper divisors (1).

31378491857 is an equidigital number, since it uses as much as digits as its factorization.

31378491857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5080320, while the sum is 56.

The spelling of 31378491857 in words is "thirty-one billion, three hundred seventy-eight million, four hundred ninety-one thousand, eight hundred fifty-seven".