201721231 has 2 divisors, whose sum is σ = 201721232. Its totient is φ = 201721230.

The previous prime is 201721199. The next prime is 201721237. The reversal of 201721231 is 132127102.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 201721231 - 2⁵ = 201721199 is a prime.

It is a super-2 number, since 2×201721231² = 81382910072310722, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 201721199 and 201721208.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (201721237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100860615 + 100860616.

It is an arithmetic number, because the mean of its divisors is an integer number (100860616).

Almost surely, 2^201721231 is an apocalyptic number.

201721231 is a deficient number, since it is larger than the sum of its proper divisors (1).

201721231 is an equidigital number, since it uses as much as digits as its factorization.

201721231 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 201721231 is about 14202.8599584732. The cubic root of 201721231 is about 586.4763945132.

Adding to 201721231 its reverse (132127102), we get a palindrome (333848333).

The spelling of 201721231 in words is "two hundred one million, seven hundred twenty-one thousand, two hundred thirty-one".