20197221 has 8 divisors (see below), whose sum is σ = 29377824. Its totient is φ = 12240720.

The previous prime is 20197211. The next prime is 20197237. The reversal of 20197221 is 12279102.

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

It is not a de Polignac number, because 20197221 - 2⁵ = 20197189 is a prime.

It is a super-2 number, since 2×20197221² = 815855472245682, which contains 22 as substring.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 20197191 and 20197200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20197201) 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 7 ways as a sum of consecutive naturals, for example, 305986 + ... + 306051.

It is an arithmetic number, because the mean of its divisors is an integer number (3672228).

Almost surely, 2^20197221 is an apocalyptic number.

It is an amenable number.

20197221 is a deficient number, since it is larger than the sum of its proper divisors (9180603).

20197221 is a wasteful number, since it uses less digits than its factorization.

20197221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 612051.

The product of its (nonzero) digits is 504, while the sum is 24.

The square root of 20197221 is about 4494.1318405227. The cubic root of 20197221 is about 272.3310784294.

The spelling of 20197221 in words is "twenty million, one hundred ninety-seven thousand, two hundred twenty-one".