21404320440 has 64 divisors (see below), whose sum is σ = 64378173600. Its totient is φ = 5693133312.

The previous prime is 21404320391. The next prime is 21404320499. The reversal of 21404320440 is 4402340412.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21404320440.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 182587 + ... + 275946.

Almost surely, 2^21404320440 is an apocalyptic number.

21404320440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21404320440 is an abundant number, since it is smaller than the sum of its proper divisors (42973853160).

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

21404320440 is a wasteful number, since it uses less digits than its factorization.

21404320440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 458936 (or 458932 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 24.

Adding to 21404320440 its reverse (4402340412), we get a palindrome (25806660852).

The spelling of 21404320440 in words is "twenty-one billion, four hundred four million, three hundred twenty thousand, four hundred forty".