261157 has 4 divisors (see below), whose sum is σ = 281260. Its totient is φ = 241056.

The previous prime is 261127. The next prime is 261167. The reversal of 261157 is 751162.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 36481 + 224676 = 191^2 + 474^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261157 is a prime.

It is a Duffinian number.

261157 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261127) 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 in 3 ways as a sum of consecutive naturals, for example, 10032 + ... + 10057.

It is an arithmetic number, because the mean of its divisors is an integer number (70315).

2²⁶¹¹⁵⁷ is an apocalyptic number.

It is an amenable number.

261157 is a deficient number, since it is larger than the sum of its proper divisors (20103).

261157 is a wasteful number, since it uses less digits than its factorization.

261157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20102.

The product of its digits is 420, while the sum is 22.

The square root of 261157 is about 511.0352238349. The cubic root of 261157 is about 63.9195767157.

The spelling of 261157 in words is "two hundred sixty-one thousand, one hundred fifty-seven".