20001001221 has 12 divisors (see below), whose sum is σ = 29960347872. Its totient is φ = 13334000652.

The previous prime is 20001001201. The next prime is 20001001291. The reversal of 20001001221 is 12210010002.

It is not a de Polignac number, because 20001001221 - 2⁶ = 20001001157 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 (20001001201) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41154081 + ... + 41154566.

It is an arithmetic number, because the mean of its divisors is an integer number (2496695656).

Almost surely, 2^20001001221 is an apocalyptic number.

It is an amenable number.

20001001221 is a deficient number, since it is larger than the sum of its proper divisors (9959346651).

20001001221 is an frugal number, since it uses more digits than its factorization.

20001001221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82308662 (or 82308650 counting only the distinct ones).

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

Adding to 20001001221 its reverse (12210010002), we get a palindrome (32211011223).

The spelling of 20001001221 in words is "twenty billion, one million, one thousand, two hundred twenty-one".