21023011 has 4 divisors (see below), whose sum is σ = 21183624. Its totient is φ = 20862400.

The previous prime is 21023003. The next prime is 21023017. The reversal of 21023011 is 11032012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21023011 - 2³ = 21023003 is a prime.

It is a super-2 number, since 2×21023011² = 883933983012242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21023017) 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, 80110 + ... + 80371.

It is an arithmetic number, because the mean of its divisors is an integer number (5295906).

Almost surely, 2^21023011 is an apocalyptic number.

21023011 is a deficient number, since it is larger than the sum of its proper divisors (160613).

21023011 is a wasteful number, since it uses less digits than its factorization.

21023011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160612.

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 21023011 is about 4585.0857134845. The cubic root of 21023011 is about 275.9931516539.

Adding to 21023011 its reverse (11032012), we get a palindrome (32055023).

Subtracting from 21023011 its reverse (11032012), we obtain a palindrome (9990999).

The spelling of 21023011 in words is "twenty-one million, twenty-three thousand, eleven".