220001021 has 4 divisors (see below), whose sum is σ = 220267872. Its totient is φ = 219734172.

The previous prime is 220000997. The next prime is 220001027. The reversal of 220001021 is 120100022.

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 a de Polignac number, because none of the positive numbers 2^k-220001021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (220001027) 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, 132185 + ... + 133838.

It is an arithmetic number, because the mean of its divisors is an integer number (55066968).

Almost surely, 2^220001021 is an apocalyptic number.

It is an amenable number.

220001021 is a deficient number, since it is larger than the sum of its proper divisors (266851).

220001021 is an equidigital number, since it uses as much as digits as its factorization.

220001021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 266850.

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

The square root of 220001021 is about 14832.4313920544. The cubic root of 220001021 is about 603.6820075547.

Adding to 220001021 its reverse (120100022), we get a palindrome (340101043).

Subtracting from 220001021 its reverse (120100022), we obtain a palindrome (99900999).

The spelling of 220001021 in words is "two hundred twenty million, one thousand, twenty-one".