1264390991 has 2 divisors, whose sum is σ = 1264390992. Its totient is φ = 1264390990.

The previous prime is 1264390987. The next prime is 1264390993. The reversal of 1264390991 is 1990934621.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1264390991 - 2² = 1264390987 is a prime.

Together with 1264390993, 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 (1264390993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 632195495 + 632195496.

It is an arithmetic number, because the mean of its divisors is an integer number (632195496).

Almost surely, 2^1264390991 is an apocalyptic number.

1264390991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1264390991 is an equidigital number, since it uses as much as digits as its factorization.

1264390991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 104976, while the sum is 44.

The square root of 1264390991 is about 35558.2759846425. The cubic root of 1264390991 is about 1081.3355080627.

The spelling of 1264390991 in words is "one billion, two hundred sixty-four million, three hundred ninety thousand, nine hundred ninety-one".