21545540144 has 20 divisors (see below), whose sum is σ = 43091081280. Its totient is φ = 10425261120.

The previous prime is 21545540123. The next prime is 21545540147. The reversal of 21545540144 is 44104554512.

21545540144 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21545540147) 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, 21718799 + ... + 21719790.

It is an arithmetic number, because the mean of its divisors is an integer number (2154554064).

Almost surely, 2^21545540144 is an apocalyptic number.

It is an amenable number.

21545540144 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21545540144 is a wasteful number, since it uses less digits than its factorization.

21545540144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43438628 (or 43438622 counting only the distinct ones).

The product of its (nonzero) digits is 64000, while the sum is 35.

The spelling of 21545540144 in words is "twenty-one billion, five hundred forty-five million, five hundred forty thousand, one hundred forty-four".