169988921 has 4 divisors (see below), whose sum is σ = 170125200. Its totient is φ = 169852644.

The previous prime is 169988893. The next prime is 169988939. The reversal of 169988921 is 129889961.

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: 129889961 = 6277 ⋅20693.

It is a cyclic number.

It is not a de Polignac number, because 169988921 - 2⁶ = 169988857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (169988941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66251 + ... + 68768.

It is an arithmetic number, because the mean of its divisors is an integer number (42531300).

Almost surely, 2^169988921 is an apocalyptic number.

It is an amenable number.

169988921 is a deficient number, since it is larger than the sum of its proper divisors (136279).

169988921 is a wasteful number, since it uses less digits than its factorization.

169988921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136278.

The product of its digits is 559872, while the sum is 53.

The square root of 169988921 is about 13037.9799432274. The cubic root of 169988921 is about 553.9537913211.

The spelling of 169988921 in words is "one hundred sixty-nine million, nine hundred eighty-eight thousand, nine hundred twenty-one".