1267666391 has 2 divisors, whose sum is σ = 1267666392. Its totient is φ = 1267666390.

The previous prime is 1267666381. The next prime is 1267666429. The reversal of 1267666391 is 1936667621.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1267666391 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1267666381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 633833195 + 633833196.

It is an arithmetic number, because the mean of its divisors is an integer number (633833196).

Almost surely, 2^1267666391 is an apocalyptic number.

1267666391 is a deficient number, since it is larger than the sum of its proper divisors (1).

1267666391 is an equidigital number, since it uses as much as digits as its factorization.

1267666391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 489888, while the sum is 47.

The square root of 1267666391 is about 35604.3029843304. The cubic root of 1267666391 is about 1082.2684347700.

The spelling of 1267666391 in words is "one billion, two hundred sixty-seven million, six hundred sixty-six thousand, three hundred ninety-one".