1291782749 has 2 divisors, whose sum is σ = 1291782750. Its totient is φ = 1291782748.

The previous prime is 1291782719. The next prime is 1291782769. The reversal of 1291782749 is 9472871921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 694322500 + 597460249 = 26350^2 + 24443^2 .

It is a cyclic number.

It is not a de Polignac number, because 1291782749 - 2²⁰ = 1290734173 is a prime.

It is a super-2 number, since 2×1291782749² = 3337405341227994002, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1291782697 and 1291782706.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1291782719) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645891374 + 645891375.

It is an arithmetic number, because the mean of its divisors is an integer number (645891375).

Almost surely, 2^1291782749 is an apocalyptic number.

It is an amenable number.

1291782749 is a deficient number, since it is larger than the sum of its proper divisors (1).

1291782749 is an equidigital number, since it uses as much as digits as its factorization.

1291782749 is an evil number, because the sum of its binary digits is even.

The product of its digits is 508032, while the sum is 50.

The square root of 1291782749 is about 35941.3793419229. The cubic root of 1291782749 is about 1089.0884697572.

The spelling of 1291782749 in words is "one billion, two hundred ninety-one million, seven hundred eighty-two thousand, seven hundred forty-nine".