1157991209 has 2 divisors, whose sum is σ = 1157991210. Its totient is φ = 1157991208.

The previous prime is 1157991181. The next prime is 1157991221. The reversal of 1157991209 is 9021997511.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1102040809 + 55950400 = 33197^2 + 7480^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1157991209 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1157991209.

It is not a weakly prime, because it can be changed into another prime (1157991229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 578995604 + 578995605.

It is an arithmetic number, because the mean of its divisors is an integer number (578995605).

Almost surely, 2^1157991209 is an apocalyptic number.

It is an amenable number.

1157991209 is a deficient number, since it is larger than the sum of its proper divisors (1).

1157991209 is an equidigital number, since it uses as much as digits as its factorization.

1157991209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 51030, while the sum is 44.

The square root of 1157991209 is about 34029.2698863787. The cubic root of 1157991209 is about 1050.1107091128.

The spelling of 1157991209 in words is "one billion, one hundred fifty-seven million, nine hundred ninety-one thousand, two hundred nine".