164320021 has 4 divisors (see below), whose sum is σ = 164672352. Its totient is φ = 163967692.

The previous prime is 164319989. The next prime is 164320049. The reversal of 164320021 is 120023461.

164320021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 cyclic number.

It is not a de Polignac number, because 164320021 - 2⁵ = 164319989 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 (164320421) 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, 175465 + ... + 176398.

It is an arithmetic number, because the mean of its divisors is an integer number (41168088).

Almost surely, 2^164320021 is an apocalyptic number.

It is an amenable number.

164320021 is a deficient number, since it is larger than the sum of its proper divisors (352331).

164320021 is an equidigital number, since it uses as much as digits as its factorization.

164320021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 352330.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 164320021 is about 12818.7371062831. The cubic root of 164320021 is about 547.7261727574.

Adding to 164320021 its reverse (120023461), we get a palindrome (284343482).

The spelling of 164320021 in words is "one hundred sixty-four million, three hundred twenty thousand, twenty-one".