21404204287 has 2 divisors, whose sum is σ = 21404204288. Its totient is φ = 21404204286.

The previous prime is 21404204209. The next prime is 21404204321. The reversal of 21404204287 is 78240240412.

It is an a-pointer prime, because the next prime (21404204321) can be obtained adding 21404204287 to its sum of digits (34).

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21404204287 - 2²⁷ = 21269986559 is a prime.

It is a super-2 number, since 2×21404204287² (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 (21404205287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10702102143 + 10702102144.

It is an arithmetic number, because the mean of its divisors is an integer number (10702102144).

Almost surely, 2^21404204287 is an apocalyptic number.

21404204287 is a deficient number, since it is larger than the sum of its proper divisors (1).

21404204287 is an equidigital number, since it uses as much as digits as its factorization.

21404204287 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 28672, while the sum is 34.

Adding to 21404204287 its reverse (78240240412), we get a palindrome (99644444699).

The spelling of 21404204287 in words is "twenty-one billion, four hundred four million, two hundred four thousand, two hundred eighty-seven".