21404320420 has 48 divisors (see below), whose sum is σ = 54074079360. Its totient is φ = 6952379904.

The previous prime is 21404320391. The next prime is 21404320499. The reversal of 21404320420 is 2402340412.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21404320391 and 21404320400.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4020709 + ... + 4026028.

It is an arithmetic number, because the mean of its divisors is an integer number (1126543320).

Almost surely, 2^21404320420 is an apocalyptic number.

21404320420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21404320420 is an abundant number, since it is smaller than the sum of its proper divisors (32669758940).

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

21404320420 is a wasteful number, since it uses less digits than its factorization.

21404320420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8046772 (or 8046770 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 22.

Adding to 21404320420 its reverse (2402340412), we get a palindrome (23806660832).

The spelling of 21404320420 in words is "twenty-one billion, four hundred four million, three hundred twenty thousand, four hundred twenty".