221021000 has 32 divisors (see below), whose sum is σ = 517191480. Its totient is φ = 88408000.

The previous prime is 221020957. The next prime is 221021033. The reversal of 221021000 is 120122.

It can be written as a sum of positive squares in 4 ways, for example, as 144528484 + 76492516 = 12022^2 + 8746^2 .

It is a Harshad number since it is a multiple of its sum of digits (8).

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 109511 + ... + 111510.

Almost surely, 2^221021000 is an apocalyptic number.

221021000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221021000 is an abundant number, since it is smaller than the sum of its proper divisors (296170480).

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

221021000 is a wasteful number, since it uses less digits than its factorization.

221021000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 221042 (or 221028 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 8.

The square root of 221021000 is about 14866.7750369742. The cubic root of 221021000 is about 604.6135090423.

Adding to 221021000 its reverse (120122), we get a palindrome (221141122).

The spelling of 221021000 in words is "two hundred twenty-one million, twenty-one thousand".