209720808931 has 4 divisors (see below), whose sum is σ = 209722483152. Its totient is φ = 209719134712.

The previous prime is 209720808919. The next prime is 209720808961. The reversal of 209720808931 is 139808027902.

209720808931 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 209720808931 - 2¹⁵ = 209720776163 is a prime.

It is a super-2 number, since 2×209720808931² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (209720808961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 632551 + ... + 905296.

It is an arithmetic number, because the mean of its divisors is an integer number (52430620788).

Almost surely, 2^209720808931 is an apocalyptic number.

209720808931 is a deficient number, since it is larger than the sum of its proper divisors (1674221).

209720808931 is a wasteful number, since it uses less digits than its factorization.

209720808931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1674220.

The product of its (nonzero) digits is 435456, while the sum is 49.

The spelling of 209720808931 in words is "two hundred nine billion, seven hundred twenty million, eight hundred eight thousand, nine hundred thirty-one".