21205473673 has 2 divisors, whose sum is σ = 21205473674. Its totient is φ = 21205473672.

The previous prime is 21205473671. The next prime is 21205473683. The reversal of 21205473673 is 37637450212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10631053449 + 10574420224 = 103107^2 + 102832^2 .

It is a cyclic number.

It is not a de Polignac number, because 21205473673 - 2¹ = 21205473671 is a prime.

It is a super-2 number, since 2×21205473673² (a number of 21 digits) contains 22 as substring.

Together with 21205473671, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21205473671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10602736836 + 10602736837.

It is an arithmetic number, because the mean of its divisors is an integer number (10602736837).

Almost surely, 2^21205473673 is an apocalyptic number.

It is an amenable number.

21205473673 is a deficient number, since it is larger than the sum of its proper divisors (1).

21205473673 is an equidigital number, since it uses as much as digits as its factorization.

21205473673 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 211680, while the sum is 40.

The spelling of 21205473673 in words is "twenty-one billion, two hundred five million, four hundred seventy-three thousand, six hundred seventy-three".