21206716073 has 2 divisors, whose sum is σ = 21206716074. Its totient is φ = 21206716072.

The previous prime is 21206716061. The next prime is 21206716087. The reversal of 21206716073 is 37061760212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17956804009 + 3249912064 = 134003^2 + 57008^2 .

It is a cyclic number.

It is not a de Polignac number, because 21206716073 - 2⁶ = 21206716009 is a prime.

It is not a weakly prime, because it can be changed into another prime (21206716043) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10603358036 + 10603358037.

It is an arithmetic number, because the mean of its divisors is an integer number (10603358037).

Almost surely, 2^21206716073 is an apocalyptic number.

It is an amenable number.

21206716073 is a deficient number, since it is larger than the sum of its proper divisors (1).

21206716073 is an equidigital number, since it uses as much as digits as its factorization.

21206716073 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 21168, while the sum is 35.

The spelling of 21206716073 in words is "twenty-one billion, two hundred six million, seven hundred sixteen thousand, seventy-three".