261181261 has 16 divisors (see below), whose sum is σ = 305359488. Its totient is φ = 220968000.

The previous prime is 261181237. The next prime is 261181273. The reversal of 261181261 is 162181162.

It is not a de Polignac number, because 261181261 - 2¹¹ = 261179213 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261181211) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4590 + ... + 23311.

It is an arithmetic number, because the mean of its divisors is an integer number (19084968).

Almost surely, 2^261181261 is an apocalyptic number.

It is an amenable number.

261181261 is a deficient number, since it is larger than the sum of its proper divisors (44178227).

261181261 is a wasteful number, since it uses less digits than its factorization.

261181261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27972.

The product of its digits is 1152, while the sum is 28.

The square root of 261181261 is about 16161.1033348593. The cubic root of 261181261 is about 639.2155599104.

Subtracting from 261181261 its reverse (162181162), we obtain a palindrome (99000099).

The spelling of 261181261 in words is "two hundred sixty-one million, one hundred eighty-one thousand, two hundred sixty-one".