1291989271 has 2 divisors, whose sum is σ = 1291989272. Its totient is φ = 1291989270.

The previous prime is 1291989247. The next prime is 1291989287. The reversal of 1291989271 is 1729891921.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (1729891921) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1291989271 - 2⁹ = 1291988759 is a prime.

It is a super-2 number, since 2×1291989271² = 3338472552758222882, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1291984271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645994635 + 645994636.

It is an arithmetic number, because the mean of its divisors is an integer number (645994636).

Almost surely, 2^1291989271 is an apocalyptic number.

1291989271 is a deficient number, since it is larger than the sum of its proper divisors (1).

1291989271 is an equidigital number, since it uses as much as digits as its factorization.

1291989271 is an evil number, because the sum of its binary digits is even.

The product of its digits is 163296, while the sum is 49.

The square root of 1291989271 is about 35944.2522665307. The cubic root of 1291989271 is about 1089.1465055076.

The spelling of 1291989271 in words is "one billion, two hundred ninety-one million, nine hundred eighty-nine thousand, two hundred seventy-one".