261637 has 2 divisors, whose sum is σ = 261638. Its totient is φ = 261636.

The previous prime is 261631. The next prime is 261641. The reversal of 261637 is 736162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 231361 + 30276 = 481^2 + 174^2 .

It is a cyclic number.

It is not a de Polignac number, because 261637 - 2⁷ = 261509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130818 + 130819.

It is an arithmetic number, because the mean of its divisors is an integer number (130819).

2²⁶¹⁶³⁷ is an apocalyptic number.

It is an amenable number.

261637 is a deficient number, since it is larger than the sum of its proper divisors (1).

261637 is an equidigital number, since it uses as much as digits as its factorization.

261637 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1512, while the sum is 25.

The square root of 261637 is about 511.5046431852. The cubic root of 261637 is about 63.9587136063.

Adding to 261637 its reverse (736162), we get a palindrome (997799).

It can be divided in two parts, 261 and 637, that added together give a palindrome (898).

The spelling of 261637 in words is "two hundred sixty-one thousand, six hundred thirty-seven".