261665044457443 has 4 divisors (see below), whose sum is σ = 285452775771768. Its totient is φ = 237877313143120.

The previous prime is 261665044457437. The next prime is 261665044457459. The reversal of 261665044457443 is 344754440566162.

It is a happy number.

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 261665044457443 - 2²¹ = 261665042360291 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261665044455443) 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, 11893865657146 + ... + 11893865657167.

It is an arithmetic number, because the mean of its divisors is an integer number (71363193942942).

Almost surely, 2^{261665044457443} is an apocalyptic number.

261665044457443 is a deficient number, since it is larger than the sum of its proper divisors (23787731314325).

261665044457443 is a wasteful number, since it uses less digits than its factorization.

261665044457443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23787731314324.

The product of its (nonzero) digits is 232243200, while the sum is 61.

The spelling of 261665044457443 in words is "two hundred sixty-one trillion, six hundred sixty-five billion, forty-four million, four hundred fifty-seven thousand, four hundred forty-three".