631716221 has 2 divisors, whose sum is σ = 631716222. Its totient is φ = 631716220.

The previous prime is 631716131. The next prime is 631716223. The reversal of 631716221 is 122617136.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 595848100 + 35868121 = 24410^2 + 5989^2 .

It is a cyclic number.

It is not a de Polignac number, because 631716221 - 2¹⁰ = 631715197 is a prime.

Together with 631716223, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (631716223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 315858110 + 315858111.

It is an arithmetic number, because the mean of its divisors is an integer number (315858111).

Almost surely, 2^631716221 is an apocalyptic number.

It is an amenable number.

631716221 is a deficient number, since it is larger than the sum of its proper divisors (1).

631716221 is an equidigital number, since it uses as much as digits as its factorization.

631716221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3024, while the sum is 29.

The square root of 631716221 is about 25133.9654849767. The cubic root of 631716221 is about 858.0396220403.

The spelling of 631716221 in words is "six hundred thirty-one million, seven hundred sixteen thousand, two hundred twenty-one".