166231537921 has 4 divisors (see below), whose sum is σ = 168099308100. Its totient is φ = 164363767744.

The previous prime is 166231537907. The next prime is 166231537943. The reversal of 166231537921 is 129735132661.

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 47978083521 + 118253454400 = 219039^2 + 343880^2 .

It is a cyclic number.

It is not a de Polignac number, because 166231537921 - 2¹³ = 166231529729 is a prime.

It is a super-2 number, since 2×166231537921² (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 (166231537991) 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, 933884956 + ... + 933885133.

It is an arithmetic number, because the mean of its divisors is an integer number (42024827025).

Almost surely, 2^166231537921 is an apocalyptic number.

It is an amenable number.

166231537921 is a deficient number, since it is larger than the sum of its proper divisors (1867770179).

166231537921 is an equidigital number, since it uses as much as digits as its factorization.

166231537921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1867770178.

The product of its digits is 408240, while the sum is 46.

The spelling of 166231537921 in words is "one hundred sixty-six billion, two hundred thirty-one million, five hundred thirty-seven thousand, nine hundred twenty-one".