221616640 has 160 divisors (see below), whose sum is σ = 618710400. Its totient is φ = 74563584.

The previous prime is 221616623. The next prime is 221616649. The reversal of 221616640 is 46616122.

It is a tau number, because it is divible by the number of its divisors (160).

It is a super-2 number, since 2×221616640² = 98227870249779200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a junction number, because it is equal to n+sod(n) for n = 221616599 and 221616608.

It is not an unprimeable number, because it can be changed into a prime (221616649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1487286 + ... + 1487434.

It is an arithmetic number, because the mean of its divisors is an integer number (3866940).

Almost surely, 2^221616640 is an apocalyptic number.

221616640 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 221616640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (309355200).

221616640 is an abundant number, since it is smaller than the sum of its proper divisors (397093760).

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

221616640 is an equidigital number, since it uses as much as digits as its factorization.

221616640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 262 (or 246 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 221616640 is about 14886.7941478345. The cubic root of 221616640 is about 605.1561557618.

The spelling of 221616640 in words is "two hundred twenty-one million, six hundred sixteen thousand, six hundred forty".