164721 has 4 divisors (see below), whose sum is σ = 219632. Its totient is φ = 109812.

The previous prime is 164707. The next prime is 164729. The reversal of 164721 is 127461.

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, and also an emirpimes, since its reverse is a distinct semiprime: 127461 = 3 ⋅42487.

It is not a de Polignac number, because 164721 - 2⁹ = 164209 is a prime.

It is a D-number.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 164721.

It is not an unprimeable number, because it can be changed into a prime (164729) 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, 27451 + ... + 27456.

It is an arithmetic number, because the mean of its divisors is an integer number (54908).

2¹⁶⁴⁷²¹ is an apocalyptic number.

It is an amenable number.

164721 is a deficient number, since it is larger than the sum of its proper divisors (54911).

164721 is an equidigital number, since it uses as much as digits as its factorization.

164721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54910.

The product of its digits is 336, while the sum is 21.

The square root of 164721 is about 405.8583496739. The cubic root of 164721 is about 54.8171337193.

The spelling of 164721 in words is "one hundred sixty-four thousand, seven hundred twenty-one".