20015221 has 8 divisors (see below), whose sum is σ = 20995200. Its totient is φ = 19044432.

The previous prime is 20015207. The next prime is 20015231. The reversal of 20015221 is 12251002.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20015221 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 (20015231) 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, 2391 + ... + 6763.

It is an arithmetic number, because the mean of its divisors is an integer number (2624400).

Almost surely, 2^20015221 is an apocalyptic number.

It is an amenable number.

20015221 is a deficient number, since it is larger than the sum of its proper divisors (979979).

20015221 is a wasteful number, since it uses less digits than its factorization.

20015221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4595.

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 20015221 is about 4473.8373908760. The cubic root of 20015221 is about 271.5106044491.

Adding to 20015221 its reverse (12251002), we get a palindrome (32266223).

The spelling of 20015221 in words is "twenty million, fifteen thousand, two hundred twenty-one".