21120001001 has 16 divisors (see below), whose sum is σ = 23175519360. Its totient is φ = 19087211520.

The previous prime is 21120000971. The next prime is 21120001003. The reversal of 21120001001 is 10010002112.

It is a cyclic number.

It is not a de Polignac number, because 21120001001 - 2¹⁰ = 21119999977 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 21120001001.

It is not an unprimeable number, because it can be changed into a prime (21120001003) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4305116 + ... + 4310018.

It is an arithmetic number, because the mean of its divisors is an integer number (1448469960).

Almost surely, 2^21120001001 is an apocalyptic number.

It is an amenable number.

21120001001 is a deficient number, since it is larger than the sum of its proper divisors (2055518359).

21120001001 is a wasteful number, since it uses less digits than its factorization.

21120001001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7136.

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 21120001001 its reverse (10010002112), we get a palindrome (31130003113).

The spelling of 21120001001 in words is "twenty-one billion, one hundred twenty million, one thousand, one".