21021201 has 48 divisors (see below), whose sum is σ = 34507200. Its totient is φ = 12737088.

The previous prime is 21021181. The next prime is 21021229. The reversal of 21021201 is 10212012.

21021201 is nontrivially palindromic in base 8.

It is not a de Polignac number, because 21021201 - 2¹⁹ = 20496913 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 133815 + ... + 133971.

It is an arithmetic number, because the mean of its divisors is an integer number (718900).

Almost surely, 2^21021201 is an apocalyptic number.

It is an amenable number.

21021201 is a deficient number, since it is larger than the sum of its proper divisors (13485999).

21021201 is a wasteful number, since it uses less digits than its factorization.

21021201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 220 (or 208 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 21021201 is about 4584.8883301559. Note that the first 3 decimals coincide. The cubic root of 21021201 is about 275.9852307787.

Adding to 21021201 its reverse (10212012), we get a palindrome (31233213).

It can be divided in two parts, 2 and 1021201, that multiplied together give a palindrome (2042402).

The spelling of 21021201 in words is "twenty-one million, twenty-one thousand, two hundred one".