221023820 has 12 divisors (see below), whose sum is σ = 464150064. Its totient is φ = 88409520.

The previous prime is 221023807. The next prime is 221023837. The reversal of 221023820 is 28320122.

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 11051191 = 221023820 / (2 + 2 + 1 + 0 + 2 + 3 + 8 + 2 + 0).

It is a junction number, because it is equal to n+sod(n) for n = 221023792 and 221023801.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5525576 + ... + 5525615.

It is an arithmetic number, because the mean of its divisors is an integer number (38679172).

Almost surely, 2^221023820 is an apocalyptic number.

221023820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221023820 is an abundant number, since it is smaller than the sum of its proper divisors (243126244).

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

221023820 is a wasteful number, since it uses less digits than its factorization.

221023820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11051200 (or 11051198 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 221023820 is about 14866.8698790297. The cubic root of 221023820 is about 604.6160804463.

Adding to 221023820 its reverse (28320122), we get a palindrome (249343942).

The spelling of 221023820 in words is "two hundred twenty-one million, twenty-three thousand, eight hundred twenty".