1391226989 has 2 divisors, whose sum is σ = 1391226990. Its totient is φ = 1391226988.

The previous prime is 1391226913. The next prime is 1391227007. The reversal of 1391226989 is 9896221931.

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., 1072890025 + 318336964 = 32755^2 + 17842^2 .

It is an emirp because it is prime and its reverse (9896221931) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1391226989 is a prime.

It is a super-2 number, since 2×1391226989² = 3871025069844012242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1391226289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 695613494 + 695613495.

It is an arithmetic number, because the mean of its divisors is an integer number (695613495).

Almost surely, 2^1391226989 is an apocalyptic number.

It is an amenable number.

1391226989 is a deficient number, since it is larger than the sum of its proper divisors (1).

1391226989 is an equidigital number, since it uses as much as digits as its factorization.

1391226989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 419904, while the sum is 50.

The square root of 1391226989 is about 37299.1553389618. The cubic root of 1391226989 is about 1116.3473129791.

The spelling of 1391226989 in words is "one billion, three hundred ninety-one million, two hundred twenty-six thousand, nine hundred eighty-nine".