1266188381 has 2 divisors, whose sum is σ = 1266188382. Its totient is φ = 1266188380.

The previous prime is 1266188353. The next prime is 1266188383. The reversal of 1266188381 is 1838816621.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 943411225 + 322777156 = 30715^2 + 17966^2 .

It is a cyclic number.

It is not a de Polignac number, because 1266188381 - 2⁶ = 1266188317 is a prime.

It is a super-2 number, since 2×1266188381² = 3206466032358802322, which contains 22 as substring.

Together with 1266188383, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1266188383) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 633094190 + 633094191.

It is an arithmetic number, because the mean of its divisors is an integer number (633094191).

Almost surely, 2^1266188381 is an apocalyptic number.

It is an amenable number.

1266188381 is a deficient number, since it is larger than the sum of its proper divisors (1).

1266188381 is an equidigital number, since it uses as much as digits as its factorization.

1266188381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 110592, while the sum is 44.

The square root of 1266188381 is about 35583.5408721504. The cubic root of 1266188381 is about 1081.8476548606.

The spelling of 1266188381 in words is "one billion, two hundred sixty-six million, one hundred eighty-eight thousand, three hundred eighty-one".