164216821 has 8 divisors (see below), whose sum is σ = 179872920. Its totient is φ = 149227008.

The previous prime is 164216813. The next prime is 164216851. The reversal of 164216821 is 128612461.

It can be written as a sum of positive squares in 4 ways, for example, as 84382596 + 79834225 = 9186^2 + 8935^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 164216821 - 2³ = 164216813 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (164216851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 166056 + ... + 167041.

It is an arithmetic number, because the mean of its divisors is an integer number (22484115).

Almost surely, 2^164216821 is an apocalyptic number.

It is an amenable number.

164216821 is a deficient number, since it is larger than the sum of its proper divisors (15656099).

164216821 is a wasteful number, since it uses less digits than its factorization.

164216821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333143.

The product of its digits is 4608, while the sum is 31.

The square root of 164216821 is about 12814.7111165254. The cubic root of 164216821 is about 547.6114835911.

The spelling of 164216821 in words is "one hundred sixty-four million, two hundred sixteen thousand, eight hundred twenty-one".