21204340440 has 32 divisors (see below), whose sum is σ = 63613021680. Its totient is φ = 5654490752.

The previous prime is 21204340429. The next prime is 21204340447. The reversal of 21204340440 is 4404340212.

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 21204340440.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204340447) by changing a digit.

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, 88351299 + ... + 88351538.

Almost surely, 2^21204340440 is an apocalyptic number.

21204340440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21204340440 is an abundant number, since it is smaller than the sum of its proper divisors (42408681240).

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

21204340440 is a wasteful number, since it uses less digits than its factorization.

21204340440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 176702851 (or 176702847 counting only the distinct ones).

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

Adding to 21204340440 its reverse (4404340212), we get a palindrome (25608680652).

The spelling of 21204340440 in words is "twenty-one billion, two hundred four million, three hundred forty thousand, four hundred forty".