161631861 has 16 divisors (see below), whose sum is σ = 224176128. Its totient is φ = 103474800.

The previous prime is 161631853. The next prime is 161631871. The reversal of 161631861 is 168136161.

161631861 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 161631861 - 2³ = 161631853 is a prime.

It is a super-2 number, since 2×161631861² = 52249716980646642, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161631871) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5550 + ... + 18816.

It is an arithmetic number, because the mean of its divisors is an integer number (14011008).

Almost surely, 2^161631861 is an apocalyptic number.

It is an amenable number.

161631861 is a deficient number, since it is larger than the sum of its proper divisors (62544267).

161631861 is a wasteful number, since it uses less digits than its factorization.

161631861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13432.

The product of its digits is 5184, while the sum is 33.

The square root of 161631861 is about 12713.4519702558. The cubic root of 161631861 is about 544.7229307372.

The spelling of 161631861 in words is "one hundred sixty-one million, six hundred thirty-one thousand, eight hundred sixty-one".