21004454 has 4 divisors (see below), whose sum is σ = 31506684. Its totient is φ = 10502226.

The previous prime is 21004447. The next prime is 21004457. The reversal of 21004454 is 45440012.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21004457) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5251112 + ... + 5251115.

It is an arithmetic number, because the mean of its divisors is an integer number (7876671).

Almost surely, 2^21004454 is an apocalyptic number.

21004454 is a deficient number, since it is larger than the sum of its proper divisors (10502230).

21004454 is a wasteful number, since it uses less digits than its factorization.

21004454 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10502229.

The product of its (nonzero) digits is 640, while the sum is 20.

The square root of 21004454 is about 4583.0616404321. The cubic root of 21004454 is about 275.9119214153.

Adding to 21004454 its reverse (45440012), we get a palindrome (66444466).

The spelling of 21004454 in words is "twenty-one million, four thousand, four hundred fifty-four".