21120109 has 2 divisors, whose sum is σ = 21120110. Its totient is φ = 21120108.

The previous prime is 21120089. The next prime is 21120119. The reversal of 21120109 is 90102112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21114025 + 6084 = 4595^2 + 78^2 .

It is a cyclic number.

It is not a de Polignac number, because 21120109 - 2¹⁹ = 20595821 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21120092 and 21120101.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21120119) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560054 + 10560055.

It is an arithmetic number, because the mean of its divisors is an integer number (10560055).

Almost surely, 2^21120109 is an apocalyptic number.

It is an amenable number.

21120109 is a deficient number, since it is larger than the sum of its proper divisors (1).

21120109 is an equidigital number, since it uses as much as digits as its factorization.

21120109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36, while the sum is 16.

The square root of 21120109 is about 4595.6619762554. The cubic root of 21120109 is about 276.4174047275.

The spelling of 21120109 in words is "twenty-one million, one hundred twenty thousand, one hundred nine".