1987391966 has 16 divisors (see below), whose sum is σ = 3415060320. Its totient is φ = 849713760.

The previous prime is 1987391957. The next prime is 1987391993. The reversal of 1987391966 is 6691937891.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 in 7 ways as a sum of consecutive naturals, for example, 162701 + ... + 174488.

It is an arithmetic number, because the mean of its divisors is an integer number (213441270).

Almost surely, 2^1987391966 is an apocalyptic number.

1987391966 is a deficient number, since it is larger than the sum of its proper divisors (1427668354).

1987391966 is a wasteful number, since it uses less digits than its factorization.

1987391966 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 337619.

The product of its digits is 4408992, while the sum is 59.

The square root of 1987391966 is about 44580.1745846738. The cubic root of 1987391966 is about 1257.2679457498.

The spelling of 1987391966 in words is "one billion, nine hundred eighty-seven million, three hundred ninety-one thousand, nine hundred sixty-six".