1987415991 has 24 divisors (see below), whose sum is σ = 3315905424. Its totient is φ = 1133640960.

The previous prime is 1987415987. The next prime is 1987416007. The reversal of 1987415991 is 1995147891.

1987415991 is a `hidden beast` number, since 1 + 9 + 8 + 7 + 41 + 599 + 1 = 666.

It is not a de Polignac number, because 1987415991 - 2² = 1987415987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1987415981) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 588756 + ... + 592121.

It is an arithmetic number, because the mean of its divisors is an integer number (138162726).

Almost surely, 2^1987415991 is an apocalyptic number.

1987415991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1987415991 is a deficient number, since it is larger than the sum of its proper divisors (1328489433).

1987415991 is a wasteful number, since it uses less digits than its factorization.

1987415991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1180911 (or 1180908 counting only the distinct ones).

The product of its digits is 816480, while the sum is 54.

The square root of 1987415991 is about 44580.4440422031. Note that the first 3 decimals coincide. The cubic root of 1987415991 is about 1257.2730119775.

The spelling of 1987415991 in words is "one billion, nine hundred eighty-seven million, four hundred fifteen thousand, nine hundred ninety-one".