20111021 has 12 divisors (see below), whose sum is σ = 23500188. Its totient is φ = 17160192.

The previous prime is 20111011. The next prime is 20111023. The reversal of 20111021 is 12011102.

It can be written as a sum of positive squares in 2 ways, for example, as 13402921 + 6708100 = 3661^2 + 2590^2 .

It is not a de Polignac number, because 20111021 - 2⁶ = 20110957 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 (20111023) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11795 + ... + 13391.

It is an arithmetic number, because the mean of its divisors is an integer number (1958349).

Almost surely, 2^20111021 is an apocalyptic number.

It is an amenable number.

20111021 is a deficient number, since it is larger than the sum of its proper divisors (3389167).

20111021 is a wasteful number, since it uses less digits than its factorization.

20111021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1868 (or 1861 counting only the distinct ones).

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

The square root of 20111021 is about 4484.5313021541. The cubic root of 20111021 is about 271.9430974177.

Adding to 20111021 its reverse (12011102), we get a palindrome (32122123).

The spelling of 20111021 in words is "twenty million, one hundred eleven thousand, twenty-one".