1240891286209 has 3 divisors (see below), whose sum is σ = 1240892400163. Its totient is φ = 1240890172256.

The previous prime is 1240891286203. The next prime is 1240891286231. The reversal of 1240891286209 is 9026821980421.

It is a happy number.

The square root of 1240891286209 is 1113953.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 211218372225 + 1029672913984 = 459585^2 + 1014728^2 .

It is not a de Polignac number, because 1240891286209 - 2¹¹ = 1240891284161 is a prime.

It is a super-2 number, since 2×1240891286209² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1240891286203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 556977 + ... + 1670929.

Almost surely, 2^{1240891286209} is an apocalyptic number.

1240891286209 is the 1113953-rd square number.

1240891286209 is the 556977-th centered octagonal number.

It is an amenable number.

1240891286209 is a deficient number, since it is larger than the sum of its proper divisors (1113954).

1240891286209 is an frugal number, since it uses more digits than its factorization.

1240891286209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2227906 (or 1113953 counting only the distinct ones).

The product of its (nonzero) digits is 995328, while the sum is 52.

The spelling of 1240891286209 in words is "one trillion, two hundred forty billion, eight hundred ninety-one million, two hundred eighty-six thousand, two hundred nine".