1291899249 has 9 divisors (see below), whose sum is σ = 1866232459. Its totient is φ = 861194280.

The previous prime is 1291899247. The next prime is 1291899251. The reversal of 1291899249 is 9429981921.

The square root of 1291899249 is 35943.

It is a perfect power (a square), and thus also a powerful number.

It is an interprime number because it is at equal distance from previous prime (1291899247) and next prime (1291899251).

It can be written as a sum of positive squares in only one way, i.e., 1249127649 + 42771600 = 35343^2 + 6540^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 1291899249 - 2¹ = 1291899247 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1291899195 and 1291899204.

It is not an unprimeable number, because it can be changed into a prime (1291899247) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 101839 + ... + 113819.

Almost surely, 2^1291899249 is an apocalyptic number.

1291899249 is the 35943-rd square number.

1291899249 is the 17972-nd centered octagonal number.

It is an amenable number.

1291899249 is a deficient number, since it is larger than the sum of its proper divisors (574333210).

1291899249 is an frugal number, since it uses more digits than its factorization.

1291899249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23968 (or 11984 counting only the distinct ones).

The product of its digits is 839808, while the sum is 54.

The cubic root of 1291899249 is about 1089.1212087486.

The spelling of 1291899249 in words is "one billion, two hundred ninety-one million, eight hundred ninety-nine thousand, two hundred forty-nine".