21361001 has 2 divisors, whose sum is σ = 21361002. Its totient is φ = 21361000.

The previous prime is 21360971. The next prime is 21361003. The reversal of 21361001 is 10016312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15960025 + 5400976 = 3995^2 + 2324^2 .

It is a cyclic number.

It is not a de Polignac number, because 21361001 - 2¹⁰ = 21359977 is a prime.

Together with 21361003, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21361003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10680500 + 10680501.

It is an arithmetic number, because the mean of its divisors is an integer number (10680501).

Almost surely, 2^21361001 is an apocalyptic number.

It is an amenable number.

21361001 is a deficient number, since it is larger than the sum of its proper divisors (1).

21361001 is an equidigital number, since it uses as much as digits as its factorization.

21361001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36, while the sum is 14.

The square root of 21361001 is about 4621.7962958140. The cubic root of 21361001 is about 277.4643559986.

Adding to 21361001 its reverse (10016312), we get a palindrome (31377313).

The spelling of 21361001 in words is "twenty-one million, three hundred sixty-one thousand, one".