161631 has 6 divisors (see below), whose sum is σ = 233480. Its totient is φ = 107748.

The previous prime is 161627. The next prime is 161639. The reversal of 161631 is 136161.

It is not a de Polignac number, because 161631 - 2² = 161627 is a prime.

It is a super-2 number, since 2×161631² = 52249160322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161639) 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 5 ways as a sum of consecutive naturals, for example, 8971 + ... + 8988.

2¹⁶¹⁶³¹ is an apocalyptic number.

161631 is a deficient number, since it is larger than the sum of its proper divisors (71849).

161631 is a wasteful number, since it uses less digits than its factorization.

161631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17965 (or 17962 counting only the distinct ones).

The product of its digits is 108, while the sum is 18.

The square root of 161631 is about 402.0335806870. The cubic root of 161631 is about 54.4721963504.

Adding to 161631 its reverse (136161), we get a palindrome (297792).

The spelling of 161631 in words is "one hundred sixty-one thousand, six hundred thirty-one".