21206573 has 8 divisors (see below), whose sum is σ = 22192896. Its totient is φ = 20239200.

The previous prime is 21206561. The next prime is 21206579. The reversal of 21206573 is 37560212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21206573 - 2⁴ = 21206557 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21206579) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2423 + ... + 6948.

It is an arithmetic number, because the mean of its divisors is an integer number (2774112).

Almost surely, 2^21206573 is an apocalyptic number.

It is an amenable number.

21206573 is a deficient number, since it is larger than the sum of its proper divisors (986323).

21206573 is an equidigital number, since it uses as much as digits as its factorization.

21206573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9475.

The product of its (nonzero) digits is 2520, while the sum is 26.

The square root of 21206573 is about 4605.0595001585. The cubic root of 21206573 is about 276.7941012267.

Adding to 21206573 its reverse (37560212), we get a palindrome (58766785).

The spelling of 21206573 in words is "twenty-one million, two hundred six thousand, five hundred seventy-three".