21200001 has 32 divisors (see below), whose sum is σ = 30759936. Its totient is φ = 12960000.

The previous prime is 21199999. The next prime is 21200021. The reversal of 21200001 is 10000212.

It is a happy number.

It is not a de Polignac number, because 21200001 - 2¹ = 21199999 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21200021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 209851 + ... + 209951.

It is an arithmetic number, because the mean of its divisors is an integer number (961248).

Almost surely, 2^21200001 is an apocalyptic number.

It is an amenable number.

21200001 is a deficient number, since it is larger than the sum of its proper divisors (9559935).

21200001 is a wasteful number, since it uses less digits than its factorization.

21200001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 233.

The product of its (nonzero) digits is 4, while the sum is 6.

The square root of 21200001 is about 4604.3458818816. The cubic root of 21200001 is about 276.7655050806.

Adding to 21200001 its reverse (10000212), we get a palindrome (31200213).

The spelling of 21200001 in words is "twenty-one million, two hundred thousand, one".