161987281 has 8 divisors (see below), whose sum is σ = 165288384. Its totient is φ = 158714640.

The previous prime is 161987279. The next prime is 161987299. The reversal of 161987281 is 182789161.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161987281 - 2¹ = 161987279 is a prime.

It is a super-2 number, since 2×161987281² = 52479758411545922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161987251) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4575 + ... + 18571.

It is an arithmetic number, because the mean of its divisors is an integer number (20661048).

Almost surely, 2^161987281 is an apocalyptic number.

It is an amenable number.

161987281 is a deficient number, since it is larger than the sum of its proper divisors (3301103).

161987281 is a wasteful number, since it uses less digits than its factorization.

161987281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14231.

The product of its digits is 48384, while the sum is 43.

The square root of 161987281 is about 12727.4224020420. The cubic root of 161987281 is about 545.1219108362.

The spelling of 161987281 in words is "one hundred sixty-one million, nine hundred eighty-seven thousand, two hundred eighty-one".