166409125761 has 4 divisors (see below), whose sum is σ = 221878834352. Its totient is φ = 110939417172.

The previous prime is 166409125739. The next prime is 166409125781. The reversal of 166409125761 is 167521904661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 167521904661 = 3 ⋅55840634887.

It is not a de Polignac number, because 166409125761 - 2³⁴ = 149229256577 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 166409125761.

It is not an unprimeable number, because it can be changed into a prime (166409125711) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27734854291 + ... + 27734854296.

It is an arithmetic number, because the mean of its divisors is an integer number (55469708588).

Almost surely, 2^166409125761 is an apocalyptic number.

It is an amenable number.

166409125761 is a deficient number, since it is larger than the sum of its proper divisors (55469708591).

166409125761 is an equidigital number, since it uses as much as digits as its factorization.

166409125761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55469708590.

The product of its (nonzero) digits is 544320, while the sum is 48.

The spelling of 166409125761 in words is "one hundred sixty-six billion, four hundred nine million, one hundred twenty-five thousand, seven hundred sixty-one".