209715426869 has 4 divisors (see below), whose sum is σ = 225847382796. Its totient is φ = 193583470944.

The previous prime is 209715426863. The next prime is 209715426883. The reversal of 209715426869 is 968624517902.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 123830091025 + 85885335844 = 351895^2 + 293062^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209715426869 is a prime.

It is a super-2 number, since 2×209715426869² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209715426863) 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 3 ways as a sum of consecutive naturals, for example, 8065977944 + ... + 8065977969.

It is an arithmetic number, because the mean of its divisors is an integer number (56461845699).

Almost surely, 2^209715426869 is an apocalyptic number.

It is an amenable number.

209715426869 is a deficient number, since it is larger than the sum of its proper divisors (16131955927).

209715426869 is a wasteful number, since it uses less digits than its factorization.

209715426869 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16131955926.

The product of its (nonzero) digits is 13063680, while the sum is 59.

The spelling of 209715426869 in words is "two hundred nine billion, seven hundred fifteen million, four hundred twenty-six thousand, eight hundred sixty-nine".