21569473 has 4 divisors (see below), whose sum is σ = 21604288. Its totient is φ = 21534660.

The previous prime is 21569453. The next prime is 21569477. The reversal of 21569473 is 37496512.

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 21569473 - 2⁵ = 21569441 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21569477) 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, 16461 + ... + 17722.

It is an arithmetic number, because the mean of its divisors is an integer number (5401072).

Almost surely, 2^21569473 is an apocalyptic number.

It is an amenable number.

21569473 is a deficient number, since it is larger than the sum of its proper divisors (34815).

21569473 is an equidigital number, since it uses as much as digits as its factorization.

21569473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34814.

The product of its digits is 45360, while the sum is 37.

The square root of 21569473 is about 4644.2946719604. The cubic root of 21569473 is about 278.3640702148.

The spelling of 21569473 in words is "twenty-one million, five hundred sixty-nine thousand, four hundred seventy-three".