7887891281 has 4 divisors (see below), whose sum is σ = 7925274864. Its totient is φ = 7850507700.

The previous prime is 7887891269. The next prime is 7887891283. The reversal of 7887891281 is 1821987887.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7887891281 is a prime.

It is a super-2 number, since 2×7887891281² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 7887891281.

It is not an unprimeable number, because it can be changed into a prime (7887891283) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18691475 + ... + 18691896.

It is an arithmetic number, because the mean of its divisors is an integer number (1981318716).

Almost surely, 2^7887891281 is an apocalyptic number.

It is an amenable number.

7887891281 is a deficient number, since it is larger than the sum of its proper divisors (37383583).

7887891281 is a wasteful number, since it uses less digits than its factorization.

7887891281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37383582.

The product of its digits is 3612672, while the sum is 59.

The square root of 7887891281 is about 88813.8011854014. The cubic root of 7887891281 is about 1990.6136236342.

The spelling of 7887891281 in words is "seven billion, eight hundred eighty-seven million, eight hundred ninety-one thousand, two hundred eighty-one".