210217137210821 has 8 divisors (see below), whose sum is σ = 226389129166200. Its totient is φ = 194045351389632.

The previous prime is 210217137210793. The next prime is 210217137210841. The reversal of 210217137210821 is 128012731712012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 111706350625 + 210105430860196 = 334225^2 + 14495014^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 210217137210821 - 2¹⁴ = 210217137194437 is a prime.

It is a super-2 number, since 2×210217137210821² (a number of 29 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210217137210841) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49412246 + ... + 53497703.

It is an arithmetic number, because the mean of its divisors is an integer number (28298641145775).

Almost surely, 2^{210217137210821} is an apocalyptic number.

It is an amenable number.

210217137210821 is a deficient number, since it is larger than the sum of its proper divisors (16171991955379).

210217137210821 is a wasteful number, since it uses less digits than its factorization.

210217137210821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103067095.

The product of its (nonzero) digits is 18816, while the sum is 38.

Adding to 210217137210821 its reverse (128012731712012), we get a palindrome (338229868922833).

The spelling of 210217137210821 in words is "two hundred ten trillion, two hundred seventeen billion, one hundred thirty-seven million, two hundred ten thousand, eight hundred twenty-one".