1981529878 has 4 divisors (see below), whose sum is σ = 2972294820. Its totient is φ = 990764938.

The previous prime is 1981529873. The next prime is 1981529941. The reversal of 1981529878 is 8789251891.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981529873) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495382468 + ... + 495382471.

It is an arithmetic number, because the mean of its divisors is an integer number (743073705).

Almost surely, 2^1981529878 is an apocalyptic number.

1981529878 is a deficient number, since it is larger than the sum of its proper divisors (990764942).

1981529878 is an equidigital number, since it uses as much as digits as its factorization.

1981529878 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 990764941.

The product of its digits is 2903040, while the sum is 58.

The square root of 1981529878 is about 44514.3783288052. The cubic root of 1981529878 is about 1256.0305663346.

The spelling of 1981529878 in words is "one billion, nine hundred eighty-one million, five hundred twenty-nine thousand, eight hundred seventy-eight".