21100004544 has 28 divisors (see below), whose sum is σ = 55827095864. Its totient is φ = 7033334784.

The previous prime is 21100004543. The next prime is 21100004557. The reversal of 21100004544 is 44540000112.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21100004544.

It is not an unprimeable number, because it can be changed into a prime (21100004543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 54947737 + ... + 54948120.

Almost surely, 2^21100004544 is an apocalyptic number.

21100004544 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21100004544 is an abundant number, since it is smaller than the sum of its proper divisors (34727091320).

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

21100004544 is a wasteful number, since it uses less digits than its factorization.

21100004544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109895872 (or 109895862 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 21.

Adding to 21100004544 its reverse (44540000112), we get a palindrome (65640004656).

The spelling of 21100004544 in words is "twenty-one billion, one hundred million, four thousand, five hundred forty-four".