1999987331 has 2 divisors, whose sum is σ = 1999987332. Its totient is φ = 1999987330.

The previous prime is 1999987313. The next prime is 1999987337. The reversal of 1999987331 is 1337899991.

Together with previous prime (1999987313) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1999987331 - 2¹⁸ = 1999725187 is a prime.

It is a super-2 number, since 2×1999987331² = 7999898648321007122, which contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (1999987337) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999993665 + 999993666.

It is an arithmetic number, because the mean of its divisors is an integer number (999993666).

Almost surely, 2^1999987331 is an apocalyptic number.

1999987331 is a deficient number, since it is larger than the sum of its proper divisors (1).

1999987331 is an equidigital number, since it uses as much as digits as its factorization.

1999987331 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3306744, while the sum is 59.

The square root of 1999987331 is about 44721.2179060454. The cubic root of 1999987331 is about 1259.9183895660.

The spelling of 1999987331 in words is "one billion, nine hundred ninety-nine million, nine hundred eighty-seven thousand, three hundred thirty-one".