21204240040 has 128 divisors (see below), whose sum is σ = 50416680960. Its totient is φ = 8010503424.

The previous prime is 21204240037. The next prime is 21204240059. The reversal of 21204240040 is 4004240212.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 40543219 + ... + 40543741.

It is an arithmetic number, because the mean of its divisors is an integer number (393880320).

Almost surely, 2^21204240040 is an apocalyptic number.

21204240040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21204240040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25208340480).

21204240040 is an abundant number, since it is smaller than the sum of its proper divisors (29212440920).

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

21204240040 is a wasteful number, since it uses less digits than its factorization.

21204240040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1031 (or 1027 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 19.

Adding to 21204240040 its reverse (4004240212), we get a palindrome (25208480252).

The spelling of 21204240040 in words is "twenty-one billion, two hundred four million, two hundred forty thousand, forty".