21055543645 has 8 divisors (see below), whose sum is σ = 25882912440. Its totient is φ = 16433594880.

The previous prime is 21055543627. The next prime is 21055543657. The reversal of 21055543645 is 54634555012.

It can be written as a sum of positive squares in 4 ways, for example, as 9078169 + 21046465476 = 3013^2 + 145074^2 .

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

It is not a de Polignac number, because 21055543645 - 2¹⁹ = 21055019357 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21055543598 and 21055543607.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 51354780 + ... + 51355189.

It is an arithmetic number, because the mean of its divisors is an integer number (3235364055).

Almost surely, 2^21055543645 is an apocalyptic number.

It is an amenable number.

21055543645 is a deficient number, since it is larger than the sum of its proper divisors (4827368795).

21055543645 is a wasteful number, since it uses less digits than its factorization.

21055543645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102710015.

The product of its (nonzero) digits is 360000, while the sum is 40.

The spelling of 21055543645 in words is "twenty-one billion, fifty-five million, five hundred forty-three thousand, six hundred forty-five".