21001606723 has 2 divisors, whose sum is σ = 21001606724. Its totient is φ = 21001606722.

The previous prime is 21001606721. The next prime is 21001606733. The reversal of 21001606723 is 32760610012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21001606723 - 2¹ = 21001606721 is a prime.

Together with 21001606721, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21001606691 and 21001606700.

It is not a weakly prime, because it can be changed into another prime (21001606721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500803361 + 10500803362.

It is an arithmetic number, because the mean of its divisors is an integer number (10500803362).

Almost surely, 2^21001606723 is an apocalyptic number.

21001606723 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001606723 is an equidigital number, since it uses as much as digits as its factorization.

21001606723 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3024, while the sum is 28.

The spelling of 21001606723 in words is "twenty-one billion, one million, six hundred six thousand, seven hundred twenty-three".