421721856 has 288 divisors, whose sum is σ = 1370134080. Its totient is φ = 127401984.

The previous prime is 421721851. The next prime is 421721879. The reversal of 421721856 is 658127124.

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 421721856.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (421721851) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4347600 + ... + 4347696.

It is an arithmetic number, because the mean of its divisors is an integer number (4757410).

Almost surely, 2^421721856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 421721856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (685067040).

421721856 is an abundant number, since it is smaller than the sum of its proper divisors (948412224).

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

421721856 is a wasteful number, since it uses less digits than its factorization.

421721856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 176 (or 156 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 421721856 is about 20535.8675492417. The cubic root of 421721856 is about 749.9092370166.

The spelling of 421721856 in words is "four hundred twenty-one million, seven hundred twenty-one thousand, eight hundred fifty-six".