209911722971 has 16 divisors (see below), whose sum is σ = 212721327840. Its totient is φ = 207120291840.

The previous prime is 209911722929. The next prime is 209911722983. The reversal of 209911722971 is 179227119902.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 209911722971 - 2¹⁸ = 209911460827 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209911722071) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 42241775 + ... + 42246743.

It is an arithmetic number, because the mean of its divisors is an integer number (13295082990).

Almost surely, 2^209911722971 is an apocalyptic number.

209911722971 is a deficient number, since it is larger than the sum of its proper divisors (2809604869).

209911722971 is a wasteful number, since it uses less digits than its factorization.

209911722971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6686.

The product of its (nonzero) digits is 285768, while the sum is 50.

The spelling of 209911722971 in words is "two hundred nine billion, nine hundred eleven million, seven hundred twenty-two thousand, nine hundred seventy-one".