21770221 has 8 divisors (see below), whose sum is σ = 24329088. Its totient is φ = 19308000.

The previous prime is 21770179. The next prime is 21770237. The reversal of 21770221 is 12207712.

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 21770221 - 2⁷ = 21770093 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21770192 and 21770201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21770321) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23685 + ... + 24586.

It is an arithmetic number, because the mean of its divisors is an integer number (3041136).

Almost surely, 2^21770221 is an apocalyptic number.

It is an amenable number.

21770221 is a deficient number, since it is larger than the sum of its proper divisors (2558867).

21770221 is a wasteful number, since it uses less digits than its factorization.

21770221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48323.

The product of its (nonzero) digits is 392, while the sum is 22.

The square root of 21770221 is about 4665.8569416561. The cubic root of 21770221 is about 279.2249869195.

Adding to 21770221 its reverse (12207712), we get a palindrome (33977933).

The spelling of 21770221 in words is "twenty-one million, seven hundred seventy thousand, two hundred twenty-one".