21404204240 has 40 divisors (see below), whose sum is σ = 50042823840. Its totient is φ = 8513845376.

The previous prime is 21404204209. The next prime is 21404204287. The reversal of 21404204240 is 4240240412.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

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 in 7 ways as a sum of consecutive naturals, for example, 733034 + ... + 761673.

It is an arithmetic number, because the mean of its divisors is an integer number (1251070596).

Almost surely, 2^21404204240 is an apocalyptic number.

21404204240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21404204240 is an abundant number, since it is smaller than the sum of its proper divisors (28638619600).

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

21404204240 is a wasteful number, since it uses less digits than its factorization.

21404204240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1494899 (or 1494893 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 23.

Adding to 21404204240 its reverse (4240240412), we get a palindrome (25644444652).

The spelling of 21404204240 in words is "twenty-one billion, four hundred four million, two hundred four thousand, two hundred forty".