21745573 has 4 divisors (see below), whose sum is σ = 22251328. Its totient is φ = 21239820.

The previous prime is 21745561. The next prime is 21745579. The reversal of 21745573 is 37554712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21745573 - 2¹³ = 21737381 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 (21745579) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 252813 + ... + 252898.

It is an arithmetic number, because the mean of its divisors is an integer number (5562832).

Almost surely, 2^21745573 is an apocalyptic number.

It is an amenable number.

21745573 is a deficient number, since it is larger than the sum of its proper divisors (505755).

21745573 is an equidigital number, since it uses as much as digits as its factorization.

21745573 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 505754.

The product of its digits is 29400, while the sum is 34.

The square root of 21745573 is about 4663.2148781715. The cubic root of 21745573 is about 279.1195686591.

The spelling of 21745573 in words is "twenty-one million, seven hundred forty-five thousand, five hundred seventy-three".