21232043644 has 24 divisors (see below), whose sum is σ = 43928367840. Its totient is φ = 8785672896.

The previous prime is 21232043617. The next prime is 21232043647. The reversal of 21232043644 is 44634023212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21232043647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13073107 + ... + 13074730.

It is an arithmetic number, because the mean of its divisors is an integer number (1830348660).

Almost surely, 2^21232043644 is an apocalyptic number.

It is an amenable number.

21232043644 is an abundant number, since it is smaller than the sum of its proper divisors (22696324196).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21232043644 is a wasteful number, since it uses less digits than its factorization.

21232043644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26147877 (or 26147875 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 31.

Adding to 21232043644 its reverse (44634023212), we get a palindrome (65866066856).

The spelling of 21232043644 in words is "twenty-one billion, two hundred thirty-two million, forty-three thousand, six hundred forty-four".