21021020111 has 16 divisors (see below), whose sum is σ = 26060887104. Its totient is φ = 16510604544.

The previous prime is 21021020099. The next prime is 21021020117. The reversal of 21021020111 is 11102012012.

It is not a de Polignac number, because 21021020111 - 2²⁶ = 20953911247 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21021020092 and 21021020101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021020117) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 830600 + ... + 855533.

It is an arithmetic number, because the mean of its divisors is an integer number (1628805444).

Almost surely, 2^21021020111 is an apocalyptic number.

21021020111 is a deficient number, since it is larger than the sum of its proper divisors (5039866993).

21021020111 is a wasteful number, since it uses less digits than its factorization.

21021020111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1686290.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21021020111 its reverse (11102012012), we get a palindrome (32123032123).

The spelling of 21021020111 in words is "twenty-one billion, twenty-one million, twenty thousand, one hundred eleven".