631861 has 2 divisors, whose sum is σ = 631862. Its totient is φ = 631860.

The previous prime is 631859. The next prime is 631867. The reversal of 631861 is 168136.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 463761 + 168100 = 681^2 + 410^2 .

It is a cyclic number.

It is not a de Polignac number, because 631861 - 2¹ = 631859 is a prime.

Together with 631859, 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 (631867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 315930 + 315931.

It is an arithmetic number, because the mean of its divisors is an integer number (315931).

2⁶³¹⁸⁶¹ is an apocalyptic number.

It is an amenable number.

631861 is a deficient number, since it is larger than the sum of its proper divisors (1).

631861 is an equidigital number, since it uses as much as digits as its factorization.

631861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 864, while the sum is 25.

The square root of 631861 is about 794.8968486540. The cubic root of 631861 is about 85.8105166571.

Adding to 631861 its reverse (168136), we get a palindrome (799997).

The spelling of 631861 in words is "six hundred thirty-one thousand, eight hundred sixty-one".