21054430021 has 4 divisors (see below), whose sum is σ = 21134485152. Its totient is φ = 20974374892.

The previous prime is 21054430009. The next prime is 21054430037. The reversal of 21054430021 is 12003445012.

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 21054430021 - 2¹⁷ = 21054298949 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21054429974 and 21054430001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21054430321) 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, 40027171 + ... + 40027696.

It is an arithmetic number, because the mean of its divisors is an integer number (5283621288).

Almost surely, 2^21054430021 is an apocalyptic number.

It is an amenable number.

21054430021 is a deficient number, since it is larger than the sum of its proper divisors (80055131).

21054430021 is an equidigital number, since it uses as much as digits as its factorization.

21054430021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80055130.

The product of its (nonzero) digits is 960, while the sum is 22.

Adding to 21054430021 its reverse (12003445012), we get a palindrome (33057875033).

The spelling of 21054430021 in words is "twenty-one billion, fifty-four million, four hundred thirty thousand, twenty-one".