1266378736621 has 4 divisors (see below), whose sum is σ = 1279434187612. Its totient is φ = 1253323285632.

The previous prime is 1266378736583. The next prime is 1266378736639.

1266378736621 is nontrivially palindromic in base 10.

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

It can be written as a sum of positive squares in 2 ways, for example, as 956847850596 + 309530886025 = 978186^2 + 556355^2 .

It is a cyclic number.

It is not a de Polignac number, because 1266378736621 - 2⁹ = 1266378736109 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 (1266378739621) 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, 6527725350 + ... + 6527725543.

It is an arithmetic number, because the mean of its divisors is an integer number (319858546903).

Almost surely, 2^{1266378736621} is an apocalyptic number.

It is an amenable number.

1266378736621 is a deficient number, since it is larger than the sum of its proper divisors (13055450991).

1266378736621 is an equidigital number, since it uses as much as digits as its factorization.

1266378736621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13055450990.

The product of its digits is 18289152, while the sum is 58.

The spelling of 1266378736621 in words is "one trillion, two hundred sixty-six billion, three hundred seventy-eight million, seven hundred thirty-six thousand, six hundred twenty-one".