31628215681 has 2 divisors, whose sum is σ = 31628215682. Its totient is φ = 31628215680.

The previous prime is 31628215649. The next prime is 31628215721. The reversal of 31628215681 is 18651282613.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27850269456 + 3777946225 = 166884^2 + 61465^2 .

It is a cyclic number.

It is not a de Polignac number, because 31628215681 - 2⁵ = 31628215649 is a prime.

It is a super-2 number, since 2×31628215681² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (31628215621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15814107840 + 15814107841.

It is an arithmetic number, because the mean of its divisors is an integer number (15814107841).

Almost surely, 2^31628215681 is an apocalyptic number.

It is an amenable number.

31628215681 is a deficient number, since it is larger than the sum of its proper divisors (1).

31628215681 is an equidigital number, since it uses as much as digits as its factorization.

31628215681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 138240, while the sum is 43.

The spelling of 31628215681 in words is "thirty-one billion, six hundred twenty-eight million, two hundred fifteen thousand, six hundred eighty-one".