21201000181 has 2 divisors, whose sum is σ = 21201000182. Its totient is φ = 21201000180.

The previous prime is 21201000157. The next prime is 21201000211. The reversal of 21201000181 is 18100010212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17520757956 + 3680242225 = 132366^2 + 60665^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201000181 - 2¹⁹ = 21200475893 is a prime.

It is a super-2 number, since 2×21201000181² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21201000151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600500090 + 10600500091.

It is an arithmetic number, because the mean of its divisors is an integer number (10600500091).

Almost surely, 2^21201000181 is an apocalyptic number.

It is an amenable number.

21201000181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201000181 is an equidigital number, since it uses as much as digits as its factorization.

21201000181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21201000181 its reverse (18100010212), we get a palindrome (39301010393).

The spelling of 21201000181 in words is "twenty-one billion, two hundred one million, one hundred eighty-one", and thus it is an aban number.