221000021 has 8 divisors (see below), whose sum is σ = 241869888. Its totient is φ = 200260000.

The previous prime is 220999997. The next prime is 221000027. The reversal of 221000021 is 120000122.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 221000021 - 2⁶ = 220999957 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 220999972 and 221000008.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221000027) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 28880 + ... + 35721.

It is an arithmetic number, because the mean of its divisors is an integer number (30233736).

Almost surely, 2^221000021 is an apocalyptic number.

It is an amenable number.

221000021 is a deficient number, since it is larger than the sum of its proper divisors (20869867).

221000021 is a wasteful number, since it uses less digits than its factorization.

221000021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64923.

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

The square root of 221000021 is about 14866.0694536249. The cubic root of 221000021 is about 604.5943787513.

Adding to 221000021 its reverse (120000122), we get a palindrome (341000143).

The spelling of 221000021 in words is "two hundred twenty-one million, twenty-one", and thus it is an aban number.