161987631 has 8 divisors (see below), whose sum is σ = 232597680. Its totient is φ = 99684672.

The previous prime is 161987603. The next prime is 161987633. The reversal of 161987631 is 136789161.

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

It is not a de Polignac number, because 161987631 - 2⁵ = 161987599 is a prime.

It is a super-2 number, since 2×161987631² = 52479985193984322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161987633) 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 7 ways as a sum of consecutive naturals, for example, 2076726 + ... + 2076803.

It is an arithmetic number, because the mean of its divisors is an integer number (29074710).

Almost surely, 2^161987631 is an apocalyptic number.

161987631 is a deficient number, since it is larger than the sum of its proper divisors (70610049).

161987631 is a wasteful number, since it uses less digits than its factorization.

161987631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4153545.

The product of its digits is 54432, while the sum is 42.

The square root of 161987631 is about 12727.4361518729. The cubic root of 161987631 is about 545.1223034443.

The spelling of 161987631 in words is "one hundred sixty-one million, nine hundred eighty-seven thousand, six hundred thirty-one".