663221820 has 96 divisors (see below), whose sum is σ = 1883669760. Its totient is φ = 174343680.

The previous prime is 663221803. The next prime is 663221821. The reversal of 663221820 is 28122366.

It is a super-2 number, since 2×663221820² = 879726365048224800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (663221821) 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, 2343399 + ... + 2343681.

It is an arithmetic number, because the mean of its divisors is an integer number (19621560).

Almost surely, 2^663221820 is an apocalyptic number.

663221820 is a gapful number since it is divisible by the number (60) 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 663221820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (941834880).

663221820 is an abundant number, since it is smaller than the sum of its proper divisors (1220447940).

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

663221820 is a wasteful number, since it uses less digits than its factorization.

663221820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 715 (or 713 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 663221820 is about 25753.0934064240. The cubic root of 663221820 is about 872.0731902066.

The spelling of 663221820 in words is "six hundred sixty-three million, two hundred twenty-one thousand, eight hundred twenty".