261265442187 has 4 divisors (see below), whose sum is σ = 348353922920. Its totient is φ = 174176961456.

The previous prime is 261265442177. The next prime is 261265442189. The reversal of 261265442187 is 781244562162.

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

It is not a de Polignac number, because 261265442187 - 2⁴ = 261265442171 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261265442189) 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, 43544240362 + ... + 43544240367.

It is an arithmetic number, because the mean of its divisors is an integer number (87088480730).

Almost surely, 2^261265442187 is an apocalyptic number.

261265442187 is a deficient number, since it is larger than the sum of its proper divisors (87088480733).

261265442187 is an equidigital number, since it uses as much as digits as its factorization.

261265442187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87088480732.

The product of its digits is 1290240, while the sum is 48.

The spelling of 261265442187 in words is "two hundred sixty-one billion, two hundred sixty-five million, four hundred forty-two thousand, one hundred eighty-seven".