21535440144 has 40 divisors (see below), whose sum is σ = 55656259200. Its totient is φ = 7175507328.

The previous prime is 21535440131. The next prime is 21535440169. The reversal of 21535440144 is 44104453512.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25782 + ... + 209130.

It is an arithmetic number, because the mean of its divisors is an integer number (1391406480).

Almost surely, 2^21535440144 is an apocalyptic number.

21535440144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21535440144 is an abundant number, since it is smaller than the sum of its proper divisors (34120819056).

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

21535440144 is a wasteful number, since it uses less digits than its factorization.

21535440144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 185807 (or 185801 counting only the distinct ones).

The product of its (nonzero) digits is 38400, while the sum is 33.

Adding to 21535440144 its reverse (44104453512), we get a palindrome (65639893656).

The spelling of 21535440144 in words is "twenty-one billion, five hundred thirty-five million, four hundred forty thousand, one hundred forty-four".