21211001 has 4 divisors (see below), whose sum is σ = 24241152. Its totient is φ = 18180852.

The previous prime is 21210989. The next prime is 21211009. The reversal of 21211001 is 10011212.

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 21211001 - 2²² = 17016697 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21211001.

It is not an unprimeable number, because it can be changed into a prime (21211009) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1515065 + ... + 1515078.

It is an arithmetic number, because the mean of its divisors is an integer number (6060288).

Almost surely, 2^21211001 is an apocalyptic number.

It is an amenable number.

21211001 is a deficient number, since it is larger than the sum of its proper divisors (3030151).

21211001 is an equidigital number, since it uses as much as digits as its factorization.

21211001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3030150.

The product of its (nonzero) digits is 4, while the sum is 8.

The square root of 21211001 is about 4605.5402506112. The cubic root of 21211001 is about 276.8133650493.

Adding to 21211001 its reverse (10011212), we get a palindrome (31222213).

The spelling of 21211001 in words is "twenty-one million, two hundred eleven thousand, one".