21133442021 has 4 divisors (see below), whose sum is σ = 21142684992. Its totient is φ = 21124199052.

The previous prime is 21133441949. The next prime is 21133442039. The reversal of 21133442021 is 12024433112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21133442021 - 2²⁶ = 21066333157 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21133442081) 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, 4618055 + ... + 4622628.

It is an arithmetic number, because the mean of its divisors is an integer number (5285671248).

Almost surely, 2^21133442021 is an apocalyptic number.

It is an amenable number.

21133442021 is a deficient number, since it is larger than the sum of its proper divisors (9242971).

21133442021 is an equidigital number, since it uses as much as digits as its factorization.

21133442021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9242970.

The product of its (nonzero) digits is 1152, while the sum is 23.

Adding to 21133442021 its reverse (12024433112), we get a palindrome (33157875133).

The spelling of 21133442021 in words is "twenty-one billion, one hundred thirty-three million, four hundred forty-two thousand, twenty-one".