20021220001 has 4 divisors (see below), whose sum is σ = 20219450004. Its totient is φ = 19822990000.

The previous prime is 20021219983. The next prime is 20021220007. The reversal of 20021220001 is 10002212002.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8135859601 + 11885360400 = 90199^2 + 109020^2 .

It is a cyclic number.

It is not a de Polignac number, because 20021220001 - 2¹⁵ = 20021187233 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20021220001.

It is not an unprimeable number, because it can be changed into a prime (20021220007) 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, 99114850 + ... + 99115051.

It is an arithmetic number, because the mean of its divisors is an integer number (5054862501).

Almost surely, 2^20021220001 is an apocalyptic number.

It is an amenable number.

20021220001 is a deficient number, since it is larger than the sum of its proper divisors (198230003).

20021220001 is a wasteful number, since it uses less digits than its factorization.

20021220001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198230002.

The product of its (nonzero) digits is 16, while the sum is 10.

Adding to 20021220001 its reverse (10002212002), we get a palindrome (30023432003).

The spelling of 20021220001 in words is "twenty billion, twenty-one million, two hundred twenty thousand, one".