21221011001 has 4 divisors (see below), whose sum is σ = 21232318692. Its totient is φ = 21209703312.

The previous prime is 21221010997. The next prime is 21221011069. The reversal of 21221011001 is 10011012212.

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 9900051001 + 11320960000 = 99499^2 + 106400^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221011001 - 2² = 21221010997 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21221010001) 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, 5651030 + ... + 5654783.

It is an arithmetic number, because the mean of its divisors is an integer number (5308079673).

Almost surely, 2^21221011001 is an apocalyptic number.

It is an amenable number.

21221011001 is a deficient number, since it is larger than the sum of its proper divisors (11307691).

21221011001 is a wasteful number, since it uses less digits than its factorization.

21221011001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11307690.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21221011001 its reverse (10011012212), we get a palindrome (31232023213).

The spelling of 21221011001 in words is "twenty-one billion, two hundred twenty-one million, eleven thousand, one".