21021111221001 has 4 divisors (see below), whose sum is σ = 28028148294672. Its totient is φ = 14014074147332.

The previous prime is 21021111220987. The next prime is 21021111221057. The reversal of 21021111221001 is 10012211112012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21021111221001 - 2⁹ = 21021111220489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21021111221801) 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, 3503518536831 + ... + 3503518536836.

It is an arithmetic number, because the mean of its divisors is an integer number (7007037073668).

Almost surely, 2^{21021111221001} is an apocalyptic number.

It is an amenable number.

21021111221001 is a deficient number, since it is larger than the sum of its proper divisors (7007037073671).

21021111221001 is an equidigital number, since it uses as much as digits as its factorization.

21021111221001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7007037073670.

The product of its (nonzero) digits is 16, while the sum is 15.

Adding to 21021111221001 its reverse (10012211112012), we get a palindrome (31033322333013).

The spelling of 21021111221001 in words is "twenty-one trillion, twenty-one billion, one hundred eleven million, two hundred twenty-one thousand, one".