21644035023 has 16 divisors (see below), whose sum is σ = 32429859840. Its totient is φ = 12740301024.

The previous prime is 21644034991. The next prime is 21644035031. The reversal of 21644035023 is 32053044612.

It is not a de Polignac number, because 21644035023 - 2⁵ = 21644034991 is a prime.

It is a super-2 number, since 2×21644035023² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21644035043) 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, 12063783 + ... + 12065576.

It is an arithmetic number, because the mean of its divisors is an integer number (2026866240).

Almost surely, 2^21644035023 is an apocalyptic number.

21644035023 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21644035023 is a deficient number, since it is larger than the sum of its proper divisors (10785824817).

21644035023 is a wasteful number, since it uses less digits than its factorization.

21644035023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24129398.

The product of its (nonzero) digits is 17280, while the sum is 30.

Adding to 21644035023 its reverse (32053044612), we get a palindrome (53697079635).

The spelling of 21644035023 in words is "twenty-one billion, six hundred forty-four million, thirty-five thousand, twenty-three".