21573317 has 2 divisors, whose sum is σ = 21573318. Its totient is φ = 21573316.

The previous prime is 21573311. The next prime is 21573353. The reversal of 21573317 is 71337512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17986081 + 3587236 = 4241^2 + 1894^2 .

It is a cyclic number.

It is not a de Polignac number, because 21573317 - 2⁴ = 21573301 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21573317.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21573311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10786658 + 10786659.

It is an arithmetic number, because the mean of its divisors is an integer number (10786659).

Almost surely, 2^21573317 is an apocalyptic number.

It is an amenable number.

21573317 is a deficient number, since it is larger than the sum of its proper divisors (1).

21573317 is an equidigital number, since it uses as much as digits as its factorization.

21573317 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4410, while the sum is 29.

The square root of 21573317 is about 4644.7084946205. The cubic root of 21573317 is about 278.3806054345.

The spelling of 21573317 in words is "twenty-one million, five hundred seventy-three thousand, three hundred seventeen".