1291615109 has 2 divisors, whose sum is σ = 1291615110. Its totient is φ = 1291615108.

The previous prime is 1291615051. The next prime is 1291615121. The reversal of 1291615109 is 9015161921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1269496900 + 22118209 = 35630^2 + 4703^2 .

It is an emirp because it is prime and its reverse (9015161921) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1291615109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1291615139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645807554 + 645807555.

It is an arithmetic number, because the mean of its divisors is an integer number (645807555).

Almost surely, 2^1291615109 is an apocalyptic number.

It is an amenable number.

1291615109 is a deficient number, since it is larger than the sum of its proper divisors (1).

1291615109 is an equidigital number, since it uses as much as digits as its factorization.

1291615109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4860, while the sum is 35.

The square root of 1291615109 is about 35939.0471353930. The cubic root of 1291615109 is about 1089.0413558779.

The spelling of 1291615109 in words is "one billion, two hundred ninety-one million, six hundred fifteen thousand, one hundred nine".