2161381816 has 32 divisors (see below), whose sum is σ = 4445466480. Its totient is φ = 977011200.

The previous prime is 2161381813. The next prime is 2161381823. The reversal of 2161381816 is 6181831612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2161381811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 51921 + ... + 83776.

Almost surely, 2^2161381816 is an apocalyptic number.

It is an amenable number.

2161381816 is an abundant number, since it is smaller than the sum of its proper divisors (2284084664).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2161381816 is a wasteful number, since it uses less digits than its factorization.

2161381816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135895 (or 135891 counting only the distinct ones).

The product of its digits is 13824, while the sum is 37.

The square root of 2161381816 is about 46490.6637509081. The cubic root of 2161381816 is about 1292.9364064005.

The spelling of 2161381816 in words is "two billion, one hundred sixty-one million, three hundred eighty-one thousand, eight hundred sixteen".