21202020001 has 4 divisors (see below), whose sum is σ = 21205328404. Its totient is φ = 21198711600.

The previous prime is 21202019983. The next prime is 21202020013. The reversal of 21202020001 is 10002020212.

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 6951390625 + 14250629376 = 83375^2 + 119376^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21202020001 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 21202020001.

It is not an unprimeable number, because it can be changed into a prime (21202020041) 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, 1644570 + ... + 1657411.

It is an arithmetic number, because the mean of its divisors is an integer number (5301332101).

Almost surely, 2^21202020001 is an apocalyptic number.

It is an amenable number.

21202020001 is a deficient number, since it is larger than the sum of its proper divisors (3308403).

21202020001 is an equidigital number, since it uses as much as digits as its factorization.

21202020001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3308402.

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

Adding to 21202020001 its reverse (10002020212), we get a palindrome (31204040213).

The spelling of 21202020001 in words is "twenty-one billion, two hundred two million, twenty thousand, one".