111820021 has 2 divisors, whose sum is σ = 111820022. Its totient is φ = 111820020.

The previous prime is 111820001. The next prime is 111820039. The reversal of 111820021 is 120028111.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 101002500 + 10817521 = 10050^2 + 3289^2 .

It is a cyclic number.

It is not a de Polignac number, because 111820021 - 2¹³ = 111811829 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 111819977 and 111820004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (111820001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 55910010 + 55910011.

It is an arithmetic number, because the mean of its divisors is an integer number (55910011).

Almost surely, 2^111820021 is an apocalyptic number.

It is an amenable number.

111820021 is a deficient number, since it is larger than the sum of its proper divisors (1).

111820021 is an equidigital number, since it uses as much as digits as its factorization.

111820021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 16.

The square root of 111820021 is about 10574.4986169558. The cubic root of 111820021 is about 481.7701150049.

Adding to 111820021 its reverse (120028111), we get a palindrome (231848132).

The spelling of 111820021 in words is "one hundred eleven million, eight hundred twenty thousand, twenty-one".