261634 has 4 divisors (see below), whose sum is σ = 392454. Its totient is φ = 130816.

The previous prime is 261631. The next prime is 261637. The reversal of 261634 is 436162.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 436162 = 2 ⋅218081.

It is an interprime number because it is at equal distance from previous prime (261631) and next prime (261637).

It can be written as a sum of positive squares in only one way, i.e., 162409 + 99225 = 403^2 + 315^2 .

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (261631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65407 + ... + 65410.

2²⁶¹⁶³⁴ is an apocalyptic number.

261634 is a deficient number, since it is larger than the sum of its proper divisors (130820).

261634 is a wasteful number, since it uses less digits than its factorization.

261634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130819.

The product of its digits is 864, while the sum is 22.

The square root of 261634 is about 511.5017106521. The cubic root of 261634 is about 63.9584691494.

Adding to 261634 its reverse (436162), we get a palindrome (697796).

The spelling of 261634 in words is "two hundred sixty-one thousand, six hundred thirty-four".