161889021 has 12 divisors (see below), whose sum is σ = 267245472. Its totient is φ = 92507976.

The previous prime is 161889001. The next prime is 161889029. The reversal of 161889021 is 120988161.

It is not a de Polignac number, because 161889021 - 2⁶ = 161888957 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161889029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1284771 + ... + 1284896.

It is an arithmetic number, because the mean of its divisors is an integer number (22270456).

Almost surely, 2^161889021 is an apocalyptic number.

It is an amenable number.

161889021 is a deficient number, since it is larger than the sum of its proper divisors (105356451).

161889021 is a wasteful number, since it uses less digits than its factorization.

161889021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2569680 (or 2569677 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 36.

The square root of 161889021 is about 12723.5616475891. The cubic root of 161889021 is about 545.0116665572.

The spelling of 161889021 in words is "one hundred sixty-one million, eight hundred eighty-nine thousand, twenty-one".