1987966691 has 2 divisors, whose sum is σ = 1987966692. Its totient is φ = 1987966690.

The previous prime is 1987966609. The next prime is 1987966711. The reversal of 1987966691 is 1966697891.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1987966691 - 2¹⁰ = 1987965667 is a prime.

It is not a weakly prime, because it can be changed into another prime (1987066691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 993983345 + 993983346.

It is an arithmetic number, because the mean of its divisors is an integer number (993983346).

Almost surely, 2^1987966691 is an apocalyptic number.

1987966691 is a deficient number, since it is larger than the sum of its proper divisors (1).

1987966691 is an equidigital number, since it uses as much as digits as its factorization.

1987966691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8817984, while the sum is 62.

The square root of 1987966691 is about 44586.6200894394. The cubic root of 1987966691 is about 1257.3891286351.

The spelling of 1987966691 in words is "one billion, nine hundred eighty-seven million, nine hundred sixty-six thousand, six hundred ninety-one".