261366263 has 4 divisors (see below), whose sum is σ = 265267320. Its totient is φ = 257465208.

The previous prime is 261366257. The next prime is 261366277. The reversal of 261366263 is 362663162.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 362663162 = 2 ⋅181331581.

It is a cyclic number.

It is not a de Polignac number, because 261366263 - 2⁴ = 261366247 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 (261366233) 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, 1950428 + ... + 1950561.

It is an arithmetic number, because the mean of its divisors is an integer number (66316830).

Almost surely, 2^261366263 is an apocalyptic number.

261366263 is a deficient number, since it is larger than the sum of its proper divisors (3901057).

261366263 is an equidigital number, since it uses as much as digits as its factorization.

261366263 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3901056.

The product of its digits is 46656, while the sum is 35.

The square root of 261366263 is about 16166.8260026512. The cubic root of 261366263 is about 639.3664490492.

The spelling of 261366263 in words is "two hundred sixty-one million, three hundred sixty-six thousand, two hundred sixty-three".