20345221 has 4 divisors (see below), whose sum is σ = 21910252. Its totient is φ = 18780192.

The previous prime is 20345167. The next prime is 20345231. The reversal of 20345221 is 12254302.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14025025 + 6320196 = 3745^2 + 2514^2 .

It is a cyclic number.

It is not a de Polignac number, because 20345221 - 2⁷ = 20345093 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20345231) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 782496 + ... + 782521.

It is an arithmetic number, because the mean of its divisors is an integer number (5477563).

Almost surely, 2^20345221 is an apocalyptic number.

It is an amenable number.

20345221 is a deficient number, since it is larger than the sum of its proper divisors (1565031).

20345221 is a wasteful number, since it uses less digits than its factorization.

20345221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1565030.

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 20345221 is about 4510.5677026290. The cubic root of 20345221 is about 272.9946507470.

Adding to 20345221 its reverse (12254302), we get a palindrome (32599523).

The spelling of 20345221 in words is "twenty million, three hundred forty-five thousand, two hundred twenty-one".