1000187981 has 4 divisors (see below), whose sum is σ = 1077125532. Its totient is φ = 923250432.

The previous prime is 1000187971. The next prime is 1000188017. The reversal of 1000187981 is 1897810001.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1897810001 = 9133 ⋅207797.

It can be written as a sum of positive squares in 2 ways, for example, as 69388900 + 930799081 = 8330^2 + 30509^2 .

It is not a de Polignac number, because 1000187981 - 2⁶ = 1000187917 is a prime.

It is a super-2 number, since 2×1000187981² = 2000751994673712722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1000187971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38468756 + ... + 38468781.

It is an arithmetic number, because the mean of its divisors is an integer number (269281383).

Almost surely, 2^1000187981 is an apocalyptic number.

It is an amenable number.

1000187981 is a deficient number, since it is larger than the sum of its proper divisors (76937551).

1000187981 is an equidigital number, since it uses as much as digits as its factorization.

1000187981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76937550.

The product of its (nonzero) digits is 4032, while the sum is 35.

The square root of 1000187981 is about 31625.7487025999. The cubic root of 1000187981 is about 1000.0626564074.

Adding to 1000187981 its reverse (1897810001), we get a palindrome (2897997982).

The spelling of 1000187981 in words is "one billion, one hundred eighty-seven thousand, nine hundred eighty-one".