261005407 has 4 divisors (see below), whose sum is σ = 281082760. Its totient is φ = 240928056.

The previous prime is 261005389. The next prime is 261005453. The reversal of 261005407 is 704500162.

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

It is a cyclic number.

It is not a de Polignac number, because 261005407 - 2¹¹ = 261003359 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 (261000407) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10038657 + ... + 10038682.

It is an arithmetic number, because the mean of its divisors is an integer number (70270690).

Almost surely, 2^261005407 is an apocalyptic number.

261005407 is a deficient number, since it is larger than the sum of its proper divisors (20077353).

261005407 is a wasteful number, since it uses less digits than its factorization.

261005407 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20077352.

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 261005407 is about 16155.6617629858. The cubic root of 261005407 is about 639.0720658858.

Adding to 261005407 its reverse (704500162), we get a palindrome (965505569).

The spelling of 261005407 in words is "two hundred sixty-one million, five thousand, four hundred seven".