1987391994 has 32 divisors (see below), whose sum is σ = 4545208320. Its totient is φ = 567501552.

The previous prime is 1987391993. The next prime is 1987392013. The reversal of 1987391994 is 4991937891.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (1987391993) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 66327 + ... + 91509.

It is an arithmetic number, because the mean of its divisors is an integer number (142037760).

Almost surely, 2^1987391994 is an apocalyptic number.

1987391994 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

1987391994 is an abundant number, since it is smaller than the sum of its proper divisors (2557816326).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1987391994 is a wasteful number, since it uses less digits than its factorization.

1987391994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27074.

The product of its digits is 4408992, while the sum is 60.

The square root of 1987391994 is about 44580.1748987148. The cubic root of 1987391994 is about 1257.2679516543.

The spelling of 1987391994 in words is "one billion, nine hundred eighty-seven million, three hundred ninety-one thousand, nine hundred ninety-four".