21022001 has 16 divisors (see below), whose sum is σ = 28226688. Its totient is φ = 15120000.

The previous prime is 21021997. The next prime is 21022007. The reversal of 21022001 is 10022012.

It is not a de Polignac number, because 21022001 - 2² = 21021997 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21022001.

It is not an unprimeable number, because it can be changed into a prime (21022007) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9500 + ... + 11501.

It is an arithmetic number, because the mean of its divisors is an integer number (1764168).

Almost surely, 2^21022001 is an apocalyptic number.

It is an amenable number.

21022001 is a deficient number, since it is larger than the sum of its proper divisors (7204687).

21022001 is a wasteful number, since it uses less digits than its factorization.

21022001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21032.

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

The square root of 21022001 is about 4584.9755724540. The cubic root of 21022001 is about 275.9887317741.

Adding to 21022001 its reverse (10022012), we get a palindrome (31044013).

The spelling of 21022001 in words is "twenty-one million, twenty-two thousand, one".