21432304261 has 2 divisors, whose sum is σ = 21432304262. Its totient is φ = 21432304260.

The previous prime is 21432304259. The next prime is 21432304307. The reversal of 21432304261 is 16240323412.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20483048161 + 949256100 = 143119^2 + 30810^2 .

It is a cyclic number.

It is not a de Polignac number, because 21432304261 - 2¹ = 21432304259 is a prime.

It is a super-2 number, since 2×21432304261² (a number of 21 digits) contains 22 as substring.

Together with 21432304259, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21432304561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10716152130 + 10716152131.

It is an arithmetic number, because the mean of its divisors is an integer number (10716152131).

Almost surely, 2^21432304261 is an apocalyptic number.

It is an amenable number.

21432304261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21432304261 is an equidigital number, since it uses as much as digits as its factorization.

21432304261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 28.

Adding to 21432304261 its reverse (16240323412), we get a palindrome (37672627673).

The spelling of 21432304261 in words is "twenty-one billion, four hundred thirty-two million, three hundred four thousand, two hundred sixty-one".