21055543647 has 8 divisors (see below), whose sum is σ = 29725473456. Its totient is φ = 13211321472.

The previous prime is 21055543627. The next prime is 21055543657. The reversal of 21055543647 is 74634555012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21055543647 - 2¹¹ = 21055541599 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21055543599 and 21055543608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055543627) 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 7 ways as a sum of consecutive naturals, for example, 206426848 + ... + 206426949.

It is an arithmetic number, because the mean of its divisors is an integer number (3715684182).

Almost surely, 2^21055543647 is an apocalyptic number.

21055543647 is a deficient number, since it is larger than the sum of its proper divisors (8669929809).

21055543647 is a wasteful number, since it uses less digits than its factorization.

21055543647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 412853817.

The product of its (nonzero) digits is 504000, while the sum is 42.

The spelling of 21055543647 in words is "twenty-one billion, fifty-five million, five hundred forty-three thousand, six hundred forty-seven".