21120101 has 4 divisors (see below), whose sum is σ = 21337932. Its totient is φ = 20902272.

The previous prime is 21120089. The next prime is 21120109. The reversal of 21120101 is 10102112.

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 15484225 + 5635876 = 3935^2 + 2374^2 .

It is a cyclic number.

It is not a de Polignac number, because 21120101 - 2¹⁸ = 20857957 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120109) 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, 108770 + ... + 108963.

It is an arithmetic number, because the mean of its divisors is an integer number (5334483).

Almost surely, 2^21120101 is an apocalyptic number.

It is an amenable number.

21120101 is a deficient number, since it is larger than the sum of its proper divisors (217831).

21120101 is an equidigital number, since it uses as much as digits as its factorization.

21120101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 217830.

The product of its (nonzero) digits is 4, while the sum is 8.

The square root of 21120101 is about 4595.6611058693. The cubic root of 21120101 is about 276.4173698265.

Adding to 21120101 its reverse (10102112), we get a palindrome (31222213).

The spelling of 21120101 in words is "twenty-one million, one hundred twenty thousand, one hundred one".