221030021 has 4 divisors (see below), whose sum is σ = 232663200. Its totient is φ = 209396844.

The previous prime is 221030009. The next prime is 221030053. The reversal of 221030021 is 120030122.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 120030122 = 2 ⋅60015061.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221030021 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 = 221029984 and 221030011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221036021) 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 3 ways as a sum of consecutive naturals, for example, 5816561 + ... + 5816598.

It is an arithmetic number, because the mean of its divisors is an integer number (58165800).

Almost surely, 2^221030021 is an apocalyptic number.

It is an amenable number.

221030021 is a deficient number, since it is larger than the sum of its proper divisors (11633179).

221030021 is a wasteful number, since it uses less digits than its factorization.

221030021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11633178.

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 221030021 is about 14867.0784285279. The cubic root of 221030021 is about 604.6217347226.

Adding to 221030021 its reverse (120030122), we get a palindrome (341060143).

The spelling of 221030021 in words is "two hundred twenty-one million, thirty thousand, twenty-one".