21212002261 has 2 divisors, whose sum is σ = 21212002262. Its totient is φ = 21212002260.

The previous prime is 21212002193. The next prime is 21212002267. The reversal of 21212002261 is 16220021212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20052259236 + 1159743025 = 141606^2 + 34055^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21212002261 is a prime.

It is a super-2 number, since 2×21212002261² (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 (21212002267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606001130 + 10606001131.

It is an arithmetic number, because the mean of its divisors is an integer number (10606001131).

Almost surely, 2^21212002261 is an apocalyptic number.

It is an amenable number.

21212002261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212002261 is an equidigital number, since it uses as much as digits as its factorization.

21212002261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 192, while the sum is 19.

Adding to 21212002261 its reverse (16220021212), we get a palindrome (37432023473).

The spelling of 21212002261 in words is "twenty-one billion, two hundred twelve million, two thousand, two hundred sixty-one".