164555981 has 4 divisors (see below), whose sum is σ = 164620572. Its totient is φ = 164491392.

The previous prime is 164555959. The next prime is 164555987. The reversal of 164555981 is 189555461.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 90079081 + 74476900 = 9491^2 + 8630^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-164555981 is a prime.

It is a super-2 number, since 2×164555981² = 54157341765744722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (164555987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28310 + ... + 33623.

It is an arithmetic number, because the mean of its divisors is an integer number (41155143).

Almost surely, 2^164555981 is an apocalyptic number.

It is an amenable number.

164555981 is a deficient number, since it is larger than the sum of its proper divisors (64591).

164555981 is an equidigital number, since it uses as much as digits as its factorization.

164555981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64590.

The product of its digits is 216000, while the sum is 44.

The square root of 164555981 is about 12827.9375193365. The cubic root of 164555981 is about 547.9882216820.

The spelling of 164555981 in words is "one hundred sixty-four million, five hundred fifty-five thousand, nine hundred eighty-one".