202117681 has 2 divisors, whose sum is σ = 202117682. Its totient is φ = 202117680.

The previous prime is 202117679. The next prime is 202117691. The reversal of 202117681 is 186711202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 144600625 + 57517056 = 12025^2 + 7584^2 .

It is a cyclic number.

It is not a de Polignac number, because 202117681 - 2¹ = 202117679 is a prime.

It is a super-2 number, since 2×202117681² = 81703113945635522, which contains 22 as substring.

Together with 202117679, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (202117651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 101058840 + 101058841.

It is an arithmetic number, because the mean of its divisors is an integer number (101058841).

Almost surely, 2^202117681 is an apocalyptic number.

202117681 is the 8992-nd centered pentagonal number.

It is an amenable number.

202117681 is a deficient number, since it is larger than the sum of its proper divisors (1).

202117681 is an equidigital number, since it uses as much as digits as its factorization.

202117681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1344, while the sum is 28.

The square root of 202117681 is about 14216.8098038906. The cubic root of 202117681 is about 586.8603508150.

Adding to 202117681 its reverse (186711202), we get a palindrome (388828883).

The spelling of 202117681 in words is "two hundred two million, one hundred seventeen thousand, six hundred eighty-one".