201721631 has 2 divisors, whose sum is σ = 201721632. Its totient is φ = 201721630.

The previous prime is 201721627. The next prime is 201721673. The reversal of 201721631 is 136127102.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 201721631 - 2² = 201721627 is a prime.

It is a super-2 number, since 2×201721631² = 81383232826600322, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a zygodrome in base 2.

It is a junction number, because it is equal to n+sod(n) for n = 201721597 and 201721606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (201721601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100860815 + 100860816.

It is an arithmetic number, because the mean of its divisors is an integer number (100860816).

Almost surely, 2^201721631 is an apocalyptic number.

201721631 is a deficient number, since it is larger than the sum of its proper divisors (1).

201721631 is an equidigital number, since it uses as much as digits as its factorization.

201721631 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 504, while the sum is 23.

The square root of 201721631 is about 14202.8740401371. The cubic root of 201721631 is about 586.4767821610.

Adding to 201721631 its reverse (136127102), we get a palindrome (337848733).

The spelling of 201721631 in words is "two hundred one million, seven hundred twenty-one thousand, six hundred thirty-one".