21204001 has 16 divisors (see below), whose sum is σ = 26208000. Its totient is φ = 16705728.

The previous prime is 21203977. The next prime is 21204013. The reversal of 21204001 is 10040212.

It is a de Polignac number, because none of the positive numbers 2^k-21204001 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21202001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35100 + ... + 35698.

It is an arithmetic number, because the mean of its divisors is an integer number (1638000).

Almost surely, 2^21204001 is an apocalyptic number.

It is an amenable number.

21204001 is a deficient number, since it is larger than the sum of its proper divisors (5003999).

21204001 is a wasteful number, since it uses less digits than its factorization.

21204001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1008.

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 21204001 is about 4604.7802336268. The cubic root of 21204001 is about 276.7829106206.

Adding to 21204001 its reverse (10040212), we get a palindrome (31244213).

The spelling of 21204001 in words is "twenty-one million, two hundred four thousand, one".