7881991887 has 32 divisors (see below), whose sum is σ = 13202601984. Its totient is φ = 4063269600.

The previous prime is 7881991847. The next prime is 7881991919.

7881991887 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 7881991887 - 2¹² = 7881987791 is a prime.

It is a super-2 number, since 2×7881991887² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7881991847) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 99973 + ... + 160494.

It is an arithmetic number, because the mean of its divisors is an integer number (412581312).

Almost surely, 2^7881991887 is an apocalyptic number.

7881991887 is a gapful number since it is divisible by the number (77) formed by its first and last digit.

7881991887 is a deficient number, since it is larger than the sum of its proper divisors (5320610097).

7881991887 is a wasteful number, since it uses less digits than its factorization.

7881991887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260619.

The product of its digits is 16257024, while the sum is 66.

The square root of 7881991887 is about 88780.5828264266. The cubic root of 7881991887 is about 1990.1172365129.

The spelling of 7881991887 in words is "seven billion, eight hundred eighty-one million, nine hundred ninety-one thousand, eight hundred eighty-seven".