21553005644 has 12 divisors (see below), whose sum is σ = 37723952784. Its totient is φ = 10774733424.

The previous prime is 21553005629. The next prime is 21553005647. The reversal of 21553005644 is 44650035512.

It is not an unprimeable number, because it can be changed into a prime (21553005647) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 414752 + ... + 463815.

It is an arithmetic number, because the mean of its divisors is an integer number (3143662732).

Almost surely, 2^21553005644 is an apocalyptic number.

It is an amenable number.

21553005644 is a deficient number, since it is larger than the sum of its proper divisors (16170947140).

21553005644 is a wasteful number, since it uses less digits than its factorization.

21553005644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 884704 (or 884702 counting only the distinct ones).

The product of its (nonzero) digits is 72000, while the sum is 35.

The spelling of 21553005644 in words is "twenty-one billion, five hundred fifty-three million, five thousand, six hundred forty-four".