21646722049 has 2 divisors, whose sum is σ = 21646722050. Its totient is φ = 21646722048.

The previous prime is 21646722011. The next prime is 21646722073. The reversal of 21646722049 is 94022764612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19918241424 + 1728480625 = 141132^2 + 41575^2 .

It is a cyclic number.

It is not a de Polignac number, because 21646722049 - 2¹¹ = 21646720001 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21646721996 and 21646722014.

It is not a weakly prime, because it can be changed into another prime (21646722089) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10823361024 + 10823361025.

It is an arithmetic number, because the mean of its divisors is an integer number (10823361025).

Almost surely, 2^21646722049 is an apocalyptic number.

It is an amenable number.

21646722049 is a deficient number, since it is larger than the sum of its proper divisors (1).

21646722049 is an equidigital number, since it uses as much as digits as its factorization.

21646722049 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 290304, while the sum is 43.

The spelling of 21646722049 in words is "twenty-one billion, six hundred forty-six million, seven hundred twenty-two thousand, forty-nine".