21564464843 has 8 divisors (see below), whose sum is σ = 21783484800. Its totient is φ = 21345830208.

The previous prime is 21564464839. The next prime is 21564464891. The reversal of 21564464843 is 34846446512.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21564464843 - 2² = 21564464839 is a prime.

It is a super-2 number, since 2×21564464843² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21564464833) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16838 + ... + 208356.

It is an arithmetic number, because the mean of its divisors is an integer number (2722935600).

Almost surely, 2^21564464843 is an apocalyptic number.

21564464843 is a deficient number, since it is larger than the sum of its proper divisors (219019957).

21564464843 is a wasteful number, since it uses less digits than its factorization.

21564464843 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 192661.

The product of its digits is 2211840, while the sum is 47.

The spelling of 21564464843 in words is "twenty-one billion, five hundred sixty-four million, four hundred sixty-four thousand, eight hundred forty-three".