261536623 has 4 divisors (see below), whose sum is σ = 267101280. Its totient is φ = 255971968.

The previous prime is 261536591. The next prime is 261536647. The reversal of 261536623 is 326635162.

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 261536623 - 2⁵ = 261536591 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 (261536323) 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, 2782258 + ... + 2782351.

It is an arithmetic number, because the mean of its divisors is an integer number (66775320).

Almost surely, 2^261536623 is an apocalyptic number.

261536623 is a deficient number, since it is larger than the sum of its proper divisors (5564657).

261536623 is an equidigital number, since it uses as much as digits as its factorization.

261536623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5564656.

The product of its digits is 38880, while the sum is 34.

The square root of 261536623 is about 16172.0939584211. The cubic root of 261536623 is about 639.5053330941.

The spelling of 261536623 in words is "two hundred sixty-one million, five hundred thirty-six thousand, six hundred twenty-three".