209929347981 has 48 divisors (see below), whose sum is σ = 320436712960. Its totient is φ = 132258096000.

The previous prime is 209929347967. The next prime is 209929347983. The reversal of 209929347981 is 189743929902.

209929347981 is a `hidden beast` number, since 209 + 9 + 2 + 9 + 347 + 9 + 81 = 666.

It is not a de Polignac number, because 209929347981 - 2⁵ = 209929347949 is a prime.

It is a super-2 number, since 2×209929347981² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209929347983) 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 47 ways as a sum of consecutive naturals, for example, 2321271 + ... + 2410011.

Almost surely, 2^209929347981 is an apocalyptic number.

It is an amenable number.

209929347981 is a deficient number, since it is larger than the sum of its proper divisors (110507364979).

209929347981 is a wasteful number, since it uses less digits than its factorization.

209929347981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88978 (or 88975 counting only the distinct ones).

The product of its (nonzero) digits is 17635968, while the sum is 63.

The spelling of 209929347981 in words is "two hundred nine billion, nine hundred twenty-nine million, three hundred forty-seven thousand, nine hundred eighty-one".