7881238640 has 80 divisors (see below), whose sum is σ = 20183993856. Its totient is φ = 2838048000.

The previous prime is 7881238639. The next prime is 7881238643. The reversal of 7881238640 is 468321887.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×7881238640² (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 (7881238643) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 47165 + ... + 134115.

Almost surely, 2^7881238640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 7881238640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10091996928).

7881238640 is an abundant number, since it is smaller than the sum of its proper divisors (12302755216).

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

7881238640 is a wasteful number, since it uses less digits than its factorization.

7881238640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87078 (or 87072 counting only the distinct ones).

The product of its (nonzero) digits is 516096, while the sum is 47.

The square root of 7881238640 is about 88776.3405418358. The cubic root of 7881238640 is about 1990.0538389346.

The spelling of 7881238640 in words is "seven billion, eight hundred eighty-one million, two hundred thirty-eight thousand, six hundred forty".