161985553 has 4 divisors (see below), whose sum is σ = 162176308. Its totient is φ = 161794800.

The previous prime is 161985511. The next prime is 161985557. The reversal of 161985553 is 355589161.

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 90954369 + 71031184 = 9537^2 + 8428^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161985553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161985557) 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, 94098 + ... + 95803.

It is an arithmetic number, because the mean of its divisors is an integer number (40544077).

Almost surely, 2^161985553 is an apocalyptic number.

It is an amenable number.

161985553 is a deficient number, since it is larger than the sum of its proper divisors (190755).

161985553 is an equidigital number, since it uses as much as digits as its factorization.

161985553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190754.

The product of its digits is 162000, while the sum is 43.

The square root of 161985553 is about 12727.3545169450. The cubic root of 161985553 is about 545.1199724659.

The spelling of 161985553 in words is "one hundred sixty-one million, nine hundred eighty-five thousand, five hundred fifty-three".