261613405 has 4 divisors (see below), whose sum is σ = 313936092. Its totient is φ = 209290720.

The previous prime is 261613399. The next prime is 261613411. The reversal of 261613405 is 504316162.

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

It is an interprime number because it is at equal distance from previous prime (261613399) and next prime (261613411).

It can be written as a sum of positive squares in 2 ways, for example, as 92275236 + 169338169 = 9606^2 + 13013^2 .

It is not a de Polignac number, because 261613405 - 2³ = 261613397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26161336 + ... + 26161345.

It is an arithmetic number, because the mean of its divisors is an integer number (78484023).

Almost surely, 2^261613405 is an apocalyptic number.

It is an amenable number.

261613405 is a deficient number, since it is larger than the sum of its proper divisors (52322687).

261613405 is an equidigital number, since it uses as much as digits as its factorization.

261613405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52322686.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 261613405 is about 16174.4676883043. The cubic root of 261613405 is about 639.5679090264.

Adding to 261613405 its reverse (504316162), we get a palindrome (765929567).

The spelling of 261613405 in words is "two hundred sixty-one million, six hundred thirteen thousand, four hundred five".