20552221 has 4 divisors (see below), whose sum is σ = 20570944. Its totient is φ = 20533500.

The previous prime is 20552177. The next prime is 20552249. The reversal of 20552221 is 12225502.

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.

It is a 3-Lehmer number, since φ(20552221) divides (20552221-1)³.

It is a cyclic number.

It is not a de Polignac number, because 20552221 - 2¹⁵ = 20519453 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20552291) 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, 7605 + ... + 9946.

It is an arithmetic number, because the mean of its divisors is an integer number (5142736).

Almost surely, 2^20552221 is an apocalyptic number.

It is an amenable number.

20552221 is a deficient number, since it is larger than the sum of its proper divisors (18723).

20552221 is a wasteful number, since it uses less digits than its factorization.

20552221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18722.

The product of its (nonzero) digits is 400, while the sum is 19.

The square root of 20552221 is about 4533.4557458963. The cubic root of 20552221 is about 273.9173787867.

Adding to 20552221 its reverse (12225502), we get a palindrome (32777723).

The spelling of 20552221 in words is "twenty million, five hundred fifty-two thousand, two hundred twenty-one".