266228813821 has 2 divisors, whose sum is σ = 266228813822. Its totient is φ = 266228813820.

The previous prime is 266228813819. The next prime is 266228813861. The reversal of 266228813821 is 128318822662.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 246423880921 + 19804932900 = 496411^2 + 140730^2 .

It is a cyclic number.

It is not a de Polignac number, because 266228813821 - 2¹ = 266228813819 is a prime.

Together with 266228813819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (266228813861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 133114406910 + 133114406911.

It is an arithmetic number, because the mean of its divisors is an integer number (133114406911).

Almost surely, 2^266228813821 is an apocalyptic number.

It is an amenable number.

266228813821 is a deficient number, since it is larger than the sum of its proper divisors (1).

266228813821 is an equidigital number, since it uses as much as digits as its factorization.

266228813821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 884736, while the sum is 49.

The spelling of 266228813821 in words is "two hundred sixty-six billion, two hundred twenty-eight million, eight hundred thirteen thousand, eight hundred twenty-one".