21002201261 has 2 divisors, whose sum is σ = 21002201262. Its totient is φ = 21002201260.

The previous prime is 21002201249. The next prime is 21002201263. The reversal of 21002201261 is 16210220012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17520493225 + 3481708036 = 132365^2 + 59006^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002201261 - 2¹⁴ = 21002184877 is a prime.

Together with 21002201263, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002201263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501100630 + 10501100631.

It is an arithmetic number, because the mean of its divisors is an integer number (10501100631).

Almost surely, 2^21002201261 is an apocalyptic number.

It is an amenable number.

21002201261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002201261 is an equidigital number, since it uses as much as digits as its factorization.

21002201261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21002201261 its reverse (16210220012), we get a palindrome (37212421273).

The spelling of 21002201261 in words is "twenty-one billion, two million, two hundred one thousand, two hundred sixty-one".