21220001 has 8 divisors (see below), whose sum is σ = 23714208. Its totient is φ = 18820000.

The previous prime is 21219997. The next prime is 21220019. The reversal of 21220001 is 10002212.

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 21220001 - 2² = 21219997 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21220501) 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, 23075 + ... + 23976.

It is an arithmetic number, because the mean of its divisors is an integer number (2964276).

Almost surely, 2^21220001 is an apocalyptic number.

It is an amenable number.

21220001 is a deficient number, since it is larger than the sum of its proper divisors (2494207).

21220001 is a wasteful number, since it uses less digits than its factorization.

21220001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47103.

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

The square root of 21220001 is about 4606.5172310543. The cubic root of 21220001 is about 276.8525108996.

Adding to 21220001 its reverse (10002212), we get a palindrome (31222213).

It can be divided in two parts, 21 and 220001, that added together give a palindrome (220022).

The spelling of 21220001 in words is "twenty-one million, two hundred twenty thousand, one".