21785664543 has 16 divisors (see below), whose sum is σ = 30759686496. Its totient is φ = 13667901440.

The previous prime is 21785664541. The next prime is 21785664557. The reversal of 21785664543 is 34546658712.

It is a cyclic number.

It is not a de Polignac number, because 21785664543 - 2¹ = 21785664541 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21785664541) 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, 584383 + ... + 620543.

It is an arithmetic number, because the mean of its divisors is an integer number (1922480406).

Almost surely, 2^21785664543 is an apocalyptic number.

21785664543 is a deficient number, since it is larger than the sum of its proper divisors (8974021953).

21785664543 is a wasteful number, since it uses less digits than its factorization.

21785664543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47994.

The product of its digits is 4838400, while the sum is 51.

The spelling of 21785664543 in words is "twenty-one billion, seven hundred eighty-five million, six hundred sixty-four thousand, five hundred forty-three".