164611981 has 2 divisors, whose sum is σ = 164611982. Its totient is φ = 164611980.

The previous prime is 164611961. The next prime is 164611999. The reversal of 164611981 is 189116461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 161036100 + 3575881 = 12690^2 + 1891^2 .

It is a cyclic number.

It is not a de Polignac number, because 164611981 - 2⁵ = 164611949 is a prime.

It is a super-2 number, since 2×164611981² = 54194208577488722, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 164611981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (164611961) 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 as a sum of consecutive naturals, namely, 82305990 + 82305991.

It is an arithmetic number, because the mean of its divisors is an integer number (82305991).

Almost surely, 2^164611981 is an apocalyptic number.

It is an amenable number.

164611981 is a deficient number, since it is larger than the sum of its proper divisors (1).

164611981 is an equidigital number, since it uses as much as digits as its factorization.

164611981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10368, while the sum is 37.

The square root of 164611981 is about 12830.1200695863. The cubic root of 164611981 is about 548.0503765381.

The spelling of 164611981 in words is "one hundred sixty-four million, six hundred eleven thousand, nine hundred eighty-one".