21110220121 has 4 divisors (see below), whose sum is σ = 21119534352. Its totient is φ = 21100905892.

The previous prime is 21110220077. The next prime is 21110220143. The reversal of 21110220121 is 12102201112.

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 21110220121 - 2⁷ = 21110219993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21110220221) 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, 4653715 + ... + 4658248.

It is an arithmetic number, because the mean of its divisors is an integer number (5279883588).

Almost surely, 2^21110220121 is an apocalyptic number.

It is an amenable number.

21110220121 is a deficient number, since it is larger than the sum of its proper divisors (9314231).

21110220121 is an equidigital number, since it uses as much as digits as its factorization.

21110220121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9314230.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21110220121 its reverse (12102201112), we get a palindrome (33212421233).

The spelling of 21110220121 in words is "twenty-one billion, one hundred ten million, two hundred twenty thousand, one hundred twenty-one".