21597673 has 2 divisors, whose sum is σ = 21597674. Its totient is φ = 21597672.

The previous prime is 21597671. The next prime is 21597691. The reversal of 21597673 is 37679512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16744464 + 4853209 = 4092^2 + 2203^2 .

It is a cyclic number.

It is not a de Polignac number, because 21597673 - 2¹ = 21597671 is a prime.

Together with 21597671, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21597671) 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, 10798836 + 10798837.

It is an arithmetic number, because the mean of its divisors is an integer number (10798837).

Almost surely, 2^21597673 is an apocalyptic number.

It is an amenable number.

21597673 is a deficient number, since it is larger than the sum of its proper divisors (1).

21597673 is an equidigital number, since it uses as much as digits as its factorization.

21597673 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 79380, while the sum is 40.

The square root of 21597673 is about 4647.3296633658. The cubic root of 21597673 is about 278.4853287528.

The spelling of 21597673 in words is "twenty-one million, five hundred ninety-seven thousand, six hundred seventy-three".