164491909561 has 32 divisors (see below), whose sum is σ = 198284378112. Its totient is φ = 133474063680.

The previous prime is 164491909531. The next prime is 164491909573. The reversal of 164491909561 is 165909194461.

It is a cyclic number.

It is not a de Polignac number, because 164491909561 - 2¹⁷ = 164491778489 is a prime.

It is a super-2 number, since 2×164491909561² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (164491909501) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 33725655 + ... + 33730531.

It is an arithmetic number, because the mean of its divisors is an integer number (6196386816).

Almost surely, 2^164491909561 is an apocalyptic number.

It is an amenable number.

164491909561 is a deficient number, since it is larger than the sum of its proper divisors (33792468551).

164491909561 is a wasteful number, since it uses less digits than its factorization.

164491909561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8269.

The product of its (nonzero) digits is 2099520, while the sum is 55.

The spelling of 164491909561 in words is "one hundred sixty-four billion, four hundred ninety-one million, nine hundred nine thousand, five hundred sixty-one".