21204420322420 has 12 divisors (see below), whose sum is σ = 44529282677124. Its totient is φ = 8481768128960.

The previous prime is 21204420322417. The next prime is 21204420322429. The reversal of 21204420322420 is 2422302440212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 10267192428516 + 10937227893904 = 3204246^2 + 3307148^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204420322429) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 530110508041 + ... + 530110508080.

It is an arithmetic number, because the mean of its divisors is an integer number (3710773556427).

Almost surely, 2^{21204420322420} is an apocalyptic number.

21204420322420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21204420322420 is an abundant number, since it is smaller than the sum of its proper divisors (23324862354704).

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

21204420322420 is a wasteful number, since it uses less digits than its factorization.

21204420322420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1060221016130 (or 1060221016128 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 28.

Adding to 21204420322420 its reverse (2422302440212), we get a palindrome (23626722762632).

The spelling of 21204420322420 in words is "twenty-one trillion, two hundred four billion, four hundred twenty million, three hundred twenty-two thousand, four hundred twenty".