21405073420 has 96 divisors (see below), whose sum is σ = 47457809280. Its totient is φ = 8098406400.

The previous prime is 21405073399. The next prime is 21405073429. The reversal of 21405073420 is 2437050412.

It is not an unprimeable number, because it can be changed into a prime (21405073429) by changing a digit.

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, 5680377 + ... + 5684143.

It is an arithmetic number, because the mean of its divisors is an integer number (494352180).

Almost surely, 2^21405073420 is an apocalyptic number.

21405073420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21405073420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23728904640).

21405073420 is an abundant number, since it is smaller than the sum of its proper divisors (26052735860).

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

21405073420 is a wasteful number, since it uses less digits than its factorization.

21405073420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4003 (or 4001 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 28.

The spelling of 21405073420 in words is "twenty-one billion, four hundred five million, seventy-three thousand, four hundred twenty".