261131601 has 16 divisors (see below), whose sum is σ = 351920448. Its totient is φ = 172224000.

The previous prime is 261131599. The next prime is 261131609. The reversal of 261131601 is 106131162.

It is not a de Polignac number, because 261131601 - 2¹ = 261131599 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261131609) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 156765 + ... + 158421.

It is an arithmetic number, because the mean of its divisors is an integer number (21995028).

Almost surely, 2^261131601 is an apocalyptic number.

It is an amenable number.

261131601 is a deficient number, since it is larger than the sum of its proper divisors (90788847).

261131601 is a wasteful number, since it uses less digits than its factorization.

261131601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2192.

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 261131601 is about 16159.5668568189. The cubic root of 261131601 is about 639.1750446801.

Adding to 261131601 its reverse (106131162), we get a palindrome (367262763).

The spelling of 261131601 in words is "two hundred sixty-one million, one hundred thirty-one thousand, six hundred one".