201721610121 has 4 divisors (see below), whose sum is σ = 268962146832. Its totient is φ = 134481073412.

The previous prime is 201721610117. The next prime is 201721610141. The reversal of 201721610121 is 121016127102.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 201721610121 - 2² = 201721610117 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 201721610091 and 201721610100.

It is not an unprimeable number, because it can be changed into a prime (201721610141) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33620268351 + ... + 33620268356.

It is an arithmetic number, because the mean of its divisors is an integer number (67240536708).

Almost surely, 2^201721610121 is an apocalyptic number.

It is an amenable number.

201721610121 is a deficient number, since it is larger than the sum of its proper divisors (67240536711).

201721610121 is an equidigital number, since it uses as much as digits as its factorization.

201721610121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67240536710.

The product of its (nonzero) digits is 336, while the sum is 24.

Adding to 201721610121 its reverse (121016127102), we get a palindrome (322737737223).

The spelling of 201721610121 in words is "two hundred one billion, seven hundred twenty-one million, six hundred ten thousand, one hundred twenty-one".