21213001 has 4 divisors (see below), whose sum is σ = 21481600. Its totient is φ = 20944404.

The previous prime is 21212993. The next prime is 21213011. The reversal of 21213001 is 10031212.

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 21213001 - 2³ = 21212993 is a prime.

It is a super-2 number, since 2×21213001² = 899982822852002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21213011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 134181 + ... + 134338.

It is an arithmetic number, because the mean of its divisors is an integer number (5370400).

Almost surely, 2^21213001 is an apocalyptic number.

It is an amenable number.

21213001 is a deficient number, since it is larger than the sum of its proper divisors (268599).

21213001 is an equidigital number, since it uses as much as digits as its factorization.

21213001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 268598.

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 21213001 is about 4605.7573752858. The cubic root of 21213001 is about 276.8220650840.

Adding to 21213001 its reverse (10031212), we get a palindrome (31244213).

The spelling of 21213001 in words is "twenty-one million, two hundred thirteen thousand, one".