261633442739 has 4 divisors (see below), whose sum is σ = 264330694824. Its totient is φ = 258936190656.

The previous prime is 261633442711. The next prime is 261633442751. The reversal of 261633442739 is 937244336162.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261633442739 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261633442769) 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, 1348625897 + ... + 1348626090.

It is an arithmetic number, because the mean of its divisors is an integer number (66082673706).

Almost surely, 2^261633442739 is an apocalyptic number.

261633442739 is a deficient number, since it is larger than the sum of its proper divisors (2697252085).

261633442739 is an equidigital number, since it uses as much as digits as its factorization.

261633442739 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2697252084.

The product of its digits is 3919104, while the sum is 50.

The spelling of 261633442739 in words is "two hundred sixty-one billion, six hundred thirty-three million, four hundred forty-two thousand, seven hundred thirty-nine".