21423449 has 4 divisors (see below), whose sum is σ = 22114560. Its totient is φ = 20732340.

The previous prime is 21423421. The next prime is 21423487. The reversal of 21423449 is 94432412.

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 21423449 - 2¹⁶ = 21357913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21420449) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 345509 + ... + 345570.

It is an arithmetic number, because the mean of its divisors is an integer number (5528640).

Almost surely, 2^21423449 is an apocalyptic number.

It is an amenable number.

21423449 is a deficient number, since it is larger than the sum of its proper divisors (691111).

21423449 is an equidigital number, since it uses as much as digits as its factorization.

21423449 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 691110.

The product of its digits is 6912, while the sum is 29.

The square root of 21423449 is about 4628.5471802716. The cubic root of 21423449 is about 277.7344781160.

The spelling of 21423449 in words is "twenty-one million, four hundred twenty-three thousand, four hundred forty-nine".