631720670081 has 2 divisors, whose sum is σ = 631720670082. Its totient is φ = 631720670080.

The previous prime is 631720670027. The next prime is 631720670083. The reversal of 631720670081 is 180076027136.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 323856599056 + 307864071025 = 569084^2 + 554855^2 .

It is a cyclic number.

It is not a de Polignac number, because 631720670081 - 2¹⁰ = 631720669057 is a prime.

It is a super-2 number, since 2×631720670081² (a number of 24 digits) contains 22 as substring.

Together with 631720670083, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (631720670083) 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, 315860335040 + 315860335041.

It is an arithmetic number, because the mean of its divisors is an integer number (315860335041).

Almost surely, 2^631720670081 is an apocalyptic number.

It is an amenable number.

631720670081 is a deficient number, since it is larger than the sum of its proper divisors (1).

631720670081 is an equidigital number, since it uses as much as digits as its factorization.

631720670081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 84672, while the sum is 41.

The spelling of 631720670081 in words is "six hundred thirty-one billion, seven hundred twenty million, six hundred seventy thousand, eighty-one".