266378821 has 2 divisors, whose sum is σ = 266378822. Its totient is φ = 266378820.

The previous prime is 266378771. The next prime is 266378843. The reversal of 266378821 is 128873662.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 249197796 + 17181025 = 15786^2 + 4145^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-266378821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (266388821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 133189410 + 133189411.

It is an arithmetic number, because the mean of its divisors is an integer number (133189411).

Almost surely, 2^266378821 is an apocalyptic number.

It is an amenable number.

266378821 is a deficient number, since it is larger than the sum of its proper divisors (1).

266378821 is an equidigital number, since it uses as much as digits as its factorization.

266378821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 193536, while the sum is 43.

The square root of 266378821 is about 16321.1158013170. The cubic root of 266378821 is about 643.4279130785.

The spelling of 266378821 in words is "two hundred sixty-six million, three hundred seventy-eight thousand, eight hundred twenty-one".