1981671815 has 8 divisors (see below), whose sum is σ = 2378655888. Its totient is φ = 1584904320.

The previous prime is 1981671767. The next prime is 1981671817. The reversal of 1981671815 is 5181761891.

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

It is not a de Polignac number, because 1981671815 - 2⁶ = 1981671751 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1981671815.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 33281 + ... + 71210.

It is an arithmetic number, because the mean of its divisors is an integer number (297331986).

Almost surely, 2^1981671815 is an apocalyptic number.

1981671815 is a deficient number, since it is larger than the sum of its proper divisors (396984073).

1981671815 is a wasteful number, since it uses less digits than its factorization.

1981671815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108289.

The product of its digits is 120960, while the sum is 47.

The square root of 1981671815 is about 44515.9725828831. The cubic root of 1981671815 is about 1256.0605554448.

The spelling of 1981671815 in words is "one billion, nine hundred eighty-one million, six hundred seventy-one thousand, eight hundred fifteen".