21000221001 has 32 divisors (see below), whose sum is σ = 32478040320. Its totient is φ = 13385699712.

The previous prime is 21000220999. The next prime is 21000221003. The reversal of 21000221001 is 10012200012.

It is an interprime number because it is at equal distance from previous prime (21000220999) and next prime (21000221003).

It is not a de Polignac number, because 21000221001 - 2¹ = 21000220999 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (21000221003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1805661 + ... + 1817253.

It is an arithmetic number, because the mean of its divisors is an integer number (1014938760).

Almost surely, 2^21000221001 is an apocalyptic number.

It is an amenable number.

21000221001 is a deficient number, since it is larger than the sum of its proper divisors (11477819319).

21000221001 is a wasteful number, since it uses less digits than its factorization.

21000221001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14542 (or 14536 counting only the distinct ones).

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

Adding to 21000221001 its reverse (10012200012), we get a palindrome (31012421013).

The spelling of 21000221001 in words is "twenty-one billion, two hundred twenty-one thousand, one".