21765812864 has 32 divisors (see below), whose sum is σ = 43479825600. Its totient is φ = 10853229312.

The previous prime is 21765812863. The next prime is 21765812867. The reversal of 21765812864 is 46821856712.

It is a tau number, because it is divible by the number of its divisors (32).

It is not an unprimeable number, because it can be changed into a prime (21765812863) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 184694 + ... + 278645.

It is an arithmetic number, because the mean of its divisors is an integer number (1358744550).

Almost surely, 2^21765812864 is an apocalyptic number.

It is an amenable number.

21765812864 is a deficient number, since it is larger than the sum of its proper divisors (21714012736).

21765812864 is an equidigital number, since it uses as much as digits as its factorization.

21765812864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 463720 (or 463708 counting only the distinct ones).

The product of its digits is 1290240, while the sum is 50.

The spelling of 21765812864 in words is "twenty-one billion, seven hundred sixty-five million, eight hundred twelve thousand, eight hundred sixty-four".