20010001221 has 24 divisors (see below), whose sum is σ = 34770931520. Its totient is φ = 10832481216.

The previous prime is 20010001201. The next prime is 20010001267. The reversal of 20010001221 is 12210001002.

It is not a de Polignac number, because 20010001221 - 2⁷ = 20010001093 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20010001201) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8357200 + ... + 8359593.

Almost surely, 2^20010001221 is an apocalyptic number.

20010001221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20010001221 is a deficient number, since it is larger than the sum of its proper divisors (14760930299).

20010001221 is a wasteful number, since it uses less digits than its factorization.

20010001221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16716825 (or 16716822 counting only the distinct ones).

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

Adding to 20010001221 its reverse (12210001002), we get a palindrome (32220002223).

The spelling of 20010001221 in words is "twenty billion, ten million, one thousand, two hundred twenty-one".