21204440340 has 96 divisors (see below), whose sum is σ = 64051223040. Its totient is φ = 5221472256.

The previous prime is 21204440339. The next prime is 21204440351. The reversal of 21204440340 is 4304440212.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21204440340.

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 31 ways as a sum of consecutive naturals, for example, 142060 + ... + 250179.

It is an arithmetic number, because the mean of its divisors is an integer number (667200240).

Almost surely, 2^21204440340 is an apocalyptic number.

21204440340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21204440340 is an abundant number, since it is smaller than the sum of its proper divisors (42846782700).

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

21204440340 is a wasteful number, since it uses less digits than its factorization.

21204440340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 392321 (or 392319 counting only the distinct ones).

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

Adding to 21204440340 its reverse (4304440212), we get a palindrome (25508880552).

The spelling of 21204440340 in words is "twenty-one billion, two hundred four million, four hundred forty thousand, three hundred forty".