1981671816 has 16 divisors (see below), whose sum is σ = 4954179600. Its totient is φ = 660557264.

The previous prime is 1981671767. The next prime is 1981671817. The reversal of 1981671816 is 6181761891.

It is not an unprimeable number, because it can be changed into a prime (1981671817) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41284806 + ... + 41284853.

It is an arithmetic number, because the mean of its divisors is an integer number (309636225).

Almost surely, 2^1981671816 is an apocalyptic number.

It is an amenable number.

1981671816 is an abundant number, since it is smaller than the sum of its proper divisors (2972507784).

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

1981671816 is a wasteful number, since it uses less digits than its factorization.

1981671816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82569668 (or 82569664 counting only the distinct ones).

The product of its digits is 145152, while the sum is 48.

The square root of 1981671816 is about 44515.9725941150. The cubic root of 1981671816 is about 1256.0605556561.

The spelling of 1981671816 in words is "one billion, nine hundred eighty-one million, six hundred seventy-one thousand, eight hundred sixteen".