21210001 has 8 divisors (see below), whose sum is σ = 21470400. Its totient is φ = 20951472.

The previous prime is 21209963. The next prime is 21210011. The reversal of 21210001 is 10001212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21210001 - 2⁷ = 21209873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21210011) 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 7 ways as a sum of consecutive naturals, for example, 41916 + ... + 42418.

It is an arithmetic number, because the mean of its divisors is an integer number (2683800).

Almost surely, 2^21210001 is an apocalyptic number.

It is an amenable number.

21210001 is a deficient number, since it is larger than the sum of its proper divisors (260399).

21210001 is a wasteful number, since it uses less digits than its factorization.

21210001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 935.

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 21210001 is about 4605.4316844352. The cubic root of 21210001 is about 276.8090148269.

Adding to 21210001 its reverse (10001212), we get a palindrome (31211213).

It can be divided in two parts, 212 and 10001, that multiplied together give a palindrome (2120212).

The spelling of 21210001 in words is "twenty-one million, two hundred ten thousand, one".