21543023404 has 24 divisors (see below), whose sum is σ = 44571774240. Its totient is φ = 8914354176.

The previous prime is 21543023387. The next prime is 21543023413. The reversal of 21543023404 is 40432034512.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13264597 + ... + 13266220.

It is an arithmetic number, because the mean of its divisors is an integer number (1857157260).

Almost surely, 2^21543023404 is an apocalyptic number.

It is an amenable number.

21543023404 is an abundant number, since it is smaller than the sum of its proper divisors (23028750836).

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

21543023404 is a wasteful number, since it uses less digits than its factorization.

21543023404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26530857 (or 26530855 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 28.

Adding to 21543023404 its reverse (40432034512), we get a palindrome (61975057916).

The spelling of 21543023404 in words is "twenty-one billion, five hundred forty-three million, twenty-three thousand, four hundred four".