21020111 has 8 divisors (see below), whose sum is σ = 24382080. Its totient is φ = 17747928.

The previous prime is 21020093. The next prime is 21020117. The reversal of 21020111 is 11102012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21020111 - 2¹⁴ = 21003727 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 (21020117) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21941 + ... + 22878.

It is an arithmetic number, because the mean of its divisors is an integer number (3047760).

Almost surely, 2^21020111 is an apocalyptic number.

21020111 is a deficient number, since it is larger than the sum of its proper divisors (3361969).

21020111 is an equidigital number, since it uses as much as digits as its factorization.

21020111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44893.

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

The square root of 21020111 is about 4584.7694598529. The cubic root of 21020111 is about 275.9804605295.

Adding to 21020111 its reverse (11102012), we get a palindrome (32122123).

It can be divided in two parts, 2102011 and 1, that added together give a palindrome (2102012).

The spelling of 21020111 in words is "twenty-one million, twenty thousand, one hundred eleven".