21101011 has 4 divisors (see below), whose sum is σ = 21111552. Its totient is φ = 21090472.

The previous prime is 21100999. The next prime is 21101027. The reversal of 21101011 is 11010112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21101011 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21100985 and 21101003.

It is not an unprimeable number, because it can be changed into a prime (21101411) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1240 + ... + 6613.

It is an arithmetic number, because the mean of its divisors is an integer number (5277888).

Almost surely, 2^21101011 is an apocalyptic number.

21101011 is a deficient number, since it is larger than the sum of its proper divisors (10541).

21101011 is an equidigital number, since it uses as much as digits as its factorization.

21101011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10540.

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

The square root of 21101011 is about 4593.5836772611. The cubic root of 21101011 is about 276.3340621716.

Adding to 21101011 its reverse (11010112), we get a palindrome (32111123).

Multiplying 21101011 by its reverse (11010112), we get a palindrome (232324494423232).

It can be divided in two parts, 2 and 1101011, that multiplied together give a palindrome (2202022).

The spelling of 21101011 in words is "twenty-one million, one hundred one thousand, eleven".