169681921 has 4 divisors (see below), whose sum is σ = 169736452. Its totient is φ = 169627392.

The previous prime is 169681909. The next prime is 169681943. The reversal of 169681921 is 129186961.

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 112890625 + 56791296 = 10625^2 + 7536^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-169681921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (169681961) 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, 22296 + ... + 28921.

It is an arithmetic number, because the mean of its divisors is an integer number (42434113).

Almost surely, 2^169681921 is an apocalyptic number.

It is an amenable number.

169681921 is a deficient number, since it is larger than the sum of its proper divisors (54531).

169681921 is an equidigital number, since it uses as much as digits as its factorization.

169681921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54530.

The product of its digits is 46656, while the sum is 43.

The square root of 169681921 is about 13026.2013265572. The cubic root of 169681921 is about 553.6201101726.

The spelling of 169681921 in words is "one hundred sixty-nine million, six hundred eighty-one thousand, nine hundred twenty-one".