21434604721 has 2 divisors, whose sum is σ = 21434604722. Its totient is φ = 21434604720.

The previous prime is 21434604707. The next prime is 21434604727. The reversal of 21434604721 is 12740643412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17842280625 + 3592324096 = 133575^2 + 59936^2 .

It is a cyclic number.

It is not a de Polignac number, because 21434604721 - 2⁷ = 21434604593 is a prime.

It is not a weakly prime, because it can be changed into another prime (21434604727) 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, 10717302360 + 10717302361.

It is an arithmetic number, because the mean of its divisors is an integer number (10717302361).

Almost surely, 2^21434604721 is an apocalyptic number.

It is an amenable number.

21434604721 is a deficient number, since it is larger than the sum of its proper divisors (1).

21434604721 is an equidigital number, since it uses as much as digits as its factorization.

21434604721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32256, while the sum is 34.

The spelling of 21434604721 in words is "twenty-one billion, four hundred thirty-four million, six hundred four thousand, seven hundred twenty-one".