421721100 has 144 divisors (see below), whose sum is σ = 1414909440. Its totient is φ = 107553600.

The previous prime is 421721089. The next prime is 421721171. The reversal of 421721100 is 1127124.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 58705 + ... + 65495.

It is an arithmetic number, because the mean of its divisors is an integer number (9825760).

Almost surely, 2^421721100 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 421721100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (707454720).

421721100 is an abundant number, since it is smaller than the sum of its proper divisors (993188340).

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

421721100 is a wasteful number, since it uses less digits than its factorization.

421721100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6837 (or 6824 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 18.

The square root of 421721100 is about 20535.8491424143. The cubic root of 421721100 is about 749.9087889078.

Adding to 421721100 its reverse (1127124), we get a palindrome (422848224).

It can be divided in two parts, 421721 and 100, that added together give a triangular number (421821 = T₉₁₈).

The spelling of 421721100 in words is "four hundred twenty-one million, seven hundred twenty-one thousand, one hundred".