221421840 has 80 divisors (see below), whose sum is σ = 708573696. Its totient is φ = 57139200.

The previous prime is 221421817. The next prime is 221421847. The reversal of 221421840 is 48124122.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 221421840.

It is not an unprimeable number, because it can be changed into a prime (221421847) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7441 + ... + 22320.

Almost surely, 2^221421840 is an apocalyptic number.

221421840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221421840 is an abundant number, since it is smaller than the sum of its proper divisors (487151856).

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

221421840 is a wasteful number, since it uses less digits than its factorization.

221421840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29808 (or 29802 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 24.

The square root of 221421840 is about 14880.2499978999. The cubic root of 221421840 is about 604.9787939656.

Adding to 221421840 its reverse (48124122), we get a palindrome (269545962).

The spelling of 221421840 in words is "two hundred twenty-one million, four hundred twenty-one thousand, eight hundred forty".