21644704523 has 8 divisors (see below), whose sum is σ = 23439906000. Its totient is φ = 19868106528.

The previous prime is 21644704519. The next prime is 21644704531. The reversal of 21644704523 is 32540744612.

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 21644704523 - 2² = 21644704519 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21644704583) 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, 4648448 + ... + 4653101.

It is an arithmetic number, because the mean of its divisors is an integer number (2929988250).

Almost surely, 2^21644704523 is an apocalyptic number.

21644704523 is a deficient number, since it is larger than the sum of its proper divisors (1795201477).

21644704523 is a wasteful number, since it uses less digits than its factorization.

21644704523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9301741.

The product of its (nonzero) digits is 161280, while the sum is 38.

The spelling of 21644704523 in words is "twenty-one billion, six hundred forty-four million, seven hundred four thousand, five hundred twenty-three".