21020021211 has 16 divisors (see below), whose sum is σ = 32196475904. Its totient is φ = 11949202944.

The previous prime is 21020021203. The next prime is 21020021213. The reversal of 21020021211 is 11212002012.

It is not a de Polignac number, because 21020021211 - 2³ = 21020021203 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21020021213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2589091 + ... + 2597196.

It is an arithmetic number, because the mean of its divisors is an integer number (2012279744).

Almost surely, 2^21020021211 is an apocalyptic number.

21020021211 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21020021211 is a deficient number, since it is larger than the sum of its proper divisors (11176454693).

21020021211 is a wasteful number, since it uses less digits than its factorization.

21020021211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5186490.

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21020021211 its reverse (11212002012), we get a palindrome (32232023223).

The spelling of 21020021211 in words is "twenty-one billion, twenty million, twenty-one thousand, two hundred eleven".