21326573 has 2 divisors, whose sum is σ = 21326574. Its totient is φ = 21326572.

The previous prime is 21326563. The next prime is 21326587. The reversal of 21326573 is 37562312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19695844 + 1630729 = 4438^2 + 1277^2 .

It is a cyclic number.

It is not a de Polignac number, because 21326573 - 2¹⁴ = 21310189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21326563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10663286 + 10663287.

It is an arithmetic number, because the mean of its divisors is an integer number (10663287).

Almost surely, 2^21326573 is an apocalyptic number.

It is an amenable number.

21326573 is a deficient number, since it is larger than the sum of its proper divisors (1).

21326573 is an equidigital number, since it uses as much as digits as its factorization.

21326573 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7560, while the sum is 29.

The square root of 21326573 is about 4618.0702679799. The cubic root of 21326573 is about 277.3152106868.

Adding to 21326573 its reverse (37562312), we get a palindrome (58888885).

The spelling of 21326573 in words is "twenty-one million, three hundred twenty-six thousand, five hundred seventy-three".