266793987781 has 4 divisors (see below), whose sum is σ = 267069887392. Its totient is φ = 266518088172.

The previous prime is 266793987769. The next prime is 266793987787. The reversal of 266793987781 is 187789397662.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-266793987781 is a prime.

It is a super-2 number, since 2×266793987781² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (266793987787) 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, 137948355 + ... + 137950288.

It is an arithmetic number, because the mean of its divisors is an integer number (66767471848).

Almost surely, 2^266793987781 is an apocalyptic number.

It is an amenable number.

266793987781 is a deficient number, since it is larger than the sum of its proper divisors (275899611).

266793987781 is an equidigital number, since it uses as much as digits as its factorization.

266793987781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 275899610.

The product of its digits is 384072192, while the sum is 73.

The spelling of 266793987781 in words is "two hundred sixty-six billion, seven hundred ninety-three million, nine hundred eighty-seven thousand, seven hundred eighty-one".