21056546021 has 16 divisors (see below), whose sum is σ = 24586416000. Its totient is φ = 18025920864.

The previous prime is 21056545981. The next prime is 21056546029. The reversal of 21056546021 is 12064565012.

It is a de Polignac number, because none of the positive numbers 2^k-21056546021 is a prime.

It is a super-3 number, since 3×21056546021³ (a number of 32 digits) contains 333 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 (21056546029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 239546 + ... + 315428.

It is an arithmetic number, because the mean of its divisors is an integer number (1536651000).

Almost surely, 2^21056546021 is an apocalyptic number.

It is an amenable number.

21056546021 is a deficient number, since it is larger than the sum of its proper divisors (3529869979).

21056546021 is an frugal number, since it uses more digits than its factorization.

21056546021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76713 (or 76699 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 32.

The spelling of 21056546021 in words is "twenty-one billion, fifty-six million, five hundred forty-six thousand, twenty-one".