21221101001 has 4 divisors (see below), whose sum is σ = 21309155604. Its totient is φ = 21133046400.

The previous prime is 21221100997. The next prime is 21221101019. The reversal of 21221101001 is 10010112212.

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 16888302025 + 4332798976 = 129955^2 + 65824^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221101001 - 2² = 21221100997 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21221101081) 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, 44026940 + ... + 44027421.

It is an arithmetic number, because the mean of its divisors is an integer number (5327288901).

Almost surely, 2^21221101001 is an apocalyptic number.

It is an amenable number.

21221101001 is a deficient number, since it is larger than the sum of its proper divisors (88054603).

21221101001 is an equidigital number, since it uses as much as digits as its factorization.

21221101001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88054602.

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

Adding to 21221101001 its reverse (10010112212), we get a palindrome (31231213213).

The spelling of 21221101001 in words is "twenty-one billion, two hundred twenty-one million, one hundred one thousand, one".