21541844872 has 8 divisors (see below), whose sum is σ = 40390959150. Its totient is φ = 10770922432.

The previous prime is 21541844869. The next prime is 21541844887. The reversal of 21541844872 is 27844814512.

It can be written as a sum of positive squares in only one way, i.e., 17932959396 + 3608885476 = 133914^2 + 60074^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a hoax number, since the sum of its digits (46) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1346365297 + ... + 1346365312.

Almost surely, 2^21541844872 is an apocalyptic number.

It is an amenable number.

21541844872 is a deficient number, since it is larger than the sum of its proper divisors (18849114278).

21541844872 is a wasteful number, since it uses less digits than its factorization.

21541844872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2692730615 (or 2692730611 counting only the distinct ones).

The product of its digits is 573440, while the sum is 46.

The spelling of 21541844872 in words is "twenty-one billion, five hundred forty-one million, eight hundred forty-four thousand, eight hundred seventy-two".