164978721 has 16 divisors (see below), whose sum is σ = 245131200. Its totient is φ = 109662624.

The previous prime is 164978713. The next prime is 164978743. The reversal of 164978721 is 127879461.

It is a happy number.

It is not a de Polignac number, because 164978721 - 2³ = 164978713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (164978791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 565 + ... + 18173.

It is an arithmetic number, because the mean of its divisors is an integer number (15320700).

Almost surely, 2^164978721 is an apocalyptic number.

It is an amenable number.

164978721 is a deficient number, since it is larger than the sum of its proper divisors (80152479).

164978721 is a wasteful number, since it uses less digits than its factorization.

164978721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17965 (or 17959 counting only the distinct ones).

The product of its digits is 169344, while the sum is 45.

The square root of 164978721 is about 12844.4042680071. The cubic root of 164978721 is about 548.4570762097.

The spelling of 164978721 in words is "one hundred sixty-four million, nine hundred seventy-eight thousand, seven hundred twenty-one".