21797447 has 4 divisors (see below), whose sum is σ = 24911376. Its totient is φ = 18683520.

The previous prime is 21797437. The next prime is 21797449. The reversal of 21797447 is 74479712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21797447 - 2¹⁶ = 21731911 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21797449) 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, 1556954 + ... + 1556967.

It is an arithmetic number, because the mean of its divisors is an integer number (6227844).

Almost surely, 2^21797447 is an apocalyptic number.

21797447 is a deficient number, since it is larger than the sum of its proper divisors (3113929).

21797447 is an equidigital number, since it uses as much as digits as its factorization.

21797447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3113928.

The product of its digits is 98784, while the sum is 41.

The square root of 21797447 is about 4668.7736077047. The cubic root of 21797447 is about 279.3413387101.

The spelling of 21797447 in words is "twenty-one million, seven hundred ninety-seven thousand, four hundred forty-seven".