21642302261 has 2 divisors, whose sum is σ = 21642302262. Its totient is φ = 21642302260.

The previous prime is 21642302239. The next prime is 21642302291. The reversal of 21642302261 is 16220324612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14354436100 + 7287866161 = 119810^2 + 85369^2 .

It is a cyclic number.

It is not a de Polignac number, because 21642302261 - 2⁶ = 21642302197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21642302221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10821151130 + 10821151131.

It is an arithmetic number, because the mean of its divisors is an integer number (10821151131).

Almost surely, 2^21642302261 is an apocalyptic number.

It is an amenable number.

21642302261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21642302261 is an equidigital number, since it uses as much as digits as its factorization.

21642302261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6912, while the sum is 29.

Adding to 21642302261 its reverse (16220324612), we get a palindrome (37862626873).

The spelling of 21642302261 in words is "twenty-one billion, six hundred forty-two million, three hundred two thousand, two hundred sixty-one".