21011011 has 8 divisors (see below), whose sum is σ = 24063840. Its totient is φ = 17971008.

The previous prime is 21011009. The next prime is 21011033. The reversal of 21011011 is 11011012.

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 21011011 - 2¹ = 21011009 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (7).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21010985 and 21011003.

It is not an unprimeable number, because it can be changed into a prime (21011071) 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, 615 + ... + 6511.

It is an arithmetic number, because the mean of its divisors is an integer number (3007980).

Almost surely, 2^21011011 is an apocalyptic number.

21011011 is a deficient number, since it is larger than the sum of its proper divisors (3052829).

21011011 is an equidigital number, since it uses as much as digits as its factorization.

21011011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6413.

The product of its (nonzero) digits is 2, while the sum is 7.

The square root of 21011011 is about 4583.7769361085. The cubic root of 21011011 is about 275.9406290765.

Adding to 21011011 its reverse (11011012), we get a palindrome (32022023).

Subtracting from 21011011 its reverse (11011012), we obtain a palindrome (9999999).

Multiplying 21011011 by its reverse (11011012), we get a palindrome (231352494253132).

The spelling of 21011011 in words is "twenty-one million, eleven thousand, eleven".