21023033221 has 4 divisors (see below), whose sum is σ = 22259682252. Its totient is φ = 19786384192.

The previous prime is 21023033209. The next prime is 21023033233. The reversal of 21023033221 is 12233032012.

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

It is an interprime number because it is at equal distance from previous prime (21023033209) and next prime (21023033233).

It can be written as a sum of positive squares in 2 ways, for example, as 7418376900 + 13604656321 = 86130^2 + 116639^2 .

It is a cyclic number.

It is not a de Polignac number, because 21023033221 - 2¹¹ = 21023031173 is a prime.

It is a super-2 number, since 2×21023033221² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21023033281) 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, 618324490 + ... + 618324523.

It is an arithmetic number, because the mean of its divisors is an integer number (5564920563).

Almost surely, 2^21023033221 is an apocalyptic number.

It is an amenable number.

21023033221 is a deficient number, since it is larger than the sum of its proper divisors (1236649031).

21023033221 is a wasteful number, since it uses less digits than its factorization.

21023033221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1236649030.

The product of its (nonzero) digits is 432, while the sum is 19.

Adding to 21023033221 its reverse (12233032012), we get a palindrome (33256065233).

The spelling of 21023033221 in words is "twenty-one billion, twenty-three million, thirty-three thousand, two hundred twenty-one".