21544193788 has 12 divisors (see below), whose sum is σ = 40602519160. Its totient is φ = 9943474032.

The previous prime is 21544193753. The next prime is 21544193899. The reversal of 21544193788 is 88739144512.

It is a Harshad number since it is a multiple of its sum of digits (52), and also a Moran number because the ratio is a prime number: 414311419 = 21544193788 / (2 + 1 + 5 + 4 + 4 + 1 + 9 + 3 + 7 + 8 + 8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 207155658 + ... + 207155761.

Almost surely, 2^21544193788 is an apocalyptic number.

It is an amenable number.

21544193788 is a deficient number, since it is larger than the sum of its proper divisors (19058325372).

21544193788 is a wasteful number, since it uses less digits than its factorization.

21544193788 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 414311436 (or 414311434 counting only the distinct ones).

The product of its digits is 1935360, while the sum is 52.

The spelling of 21544193788 in words is "twenty-one billion, five hundred forty-four million, one hundred ninety-three thousand, seven hundred eighty-eight".