21055053021 has 4 divisors (see below), whose sum is σ = 28073404032. Its totient is φ = 14036702012.

The previous prime is 21055053017. The next prime is 21055053049. The reversal of 21055053021 is 12035055012.

It is a happy number.

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 21055053021 - 2² = 21055053017 is a prime.

It is a super-4 number, since 4×21055053021⁴ (a number of 42 digits) contains 4444 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21055052982 and 21055053000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055053011) 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, 3509175501 + ... + 3509175506.

It is an arithmetic number, because the mean of its divisors is an integer number (7018351008).

Almost surely, 2^21055053021 is an apocalyptic number.

It is an amenable number.

21055053021 is a deficient number, since it is larger than the sum of its proper divisors (7018351011).

21055053021 is an equidigital number, since it uses as much as digits as its factorization.

21055053021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7018351010.

The product of its (nonzero) digits is 1500, while the sum is 24.

The spelling of 21055053021 in words is "twenty-one billion, fifty-five million, fifty-three thousand, twenty-one".