261005121 has 36 divisors (see below), whose sum is σ = 411214908. Its totient is φ = 159449472.

The previous prime is 261005119. The next prime is 261005123. The reversal of 261005121 is 121500162.

261005121 is a `hidden beast` number, since 2 + 610 + 0 + 51 + 2 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (261005119) and next prime (261005123).

It can be written as a sum of positive squares in 6 ways, for example, as 7049025 + 253956096 = 2655^2 + 15936^2 .

It is not a de Polignac number, because 261005121 - 2¹ = 261005119 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 261005094 and 261005103.

It is not an unprimeable number, because it can be changed into a prime (261005123) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 238251 + ... + 239343.

Almost surely, 2^261005121 is an apocalyptic number.

It is an amenable number.

261005121 is a deficient number, since it is larger than the sum of its proper divisors (150209787).

261005121 is a wasteful number, since it uses less digits than its factorization.

261005121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1282 (or 1266 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 261005121 is about 16155.6529115972. The cubic root of 261005121 is about 639.0718324620.

Adding to 261005121 its reverse (121500162), we get a palindrome (382505283).

The spelling of 261005121 in words is "two hundred sixty-one million, five thousand, one hundred twenty-one".