7181721138 has 16 divisors (see below), whose sum is σ = 14381206560. Its totient is φ = 2390946336.

The previous prime is 7181721109. The next prime is 7181721139. The reversal of 7181721138 is 8311271817.

It is a junction number, because it is equal to n+sod(n) for n = 7181721096 and 7181721105.

It is not an unprimeable number, because it can be changed into a prime (7181721139) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 734920 + ... + 744627.

It is an arithmetic number, because the mean of its divisors is an integer number (898825410).

Almost surely, 2^7181721138 is an apocalyptic number.

7181721138 is an abundant number, since it is smaller than the sum of its proper divisors (7199485422).

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

7181721138 is a wasteful number, since it uses less digits than its factorization.

7181721138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1480361.

The product of its digits is 18816, while the sum is 39.

The square root of 7181721138 is about 84745.0360670169. The cubic root of 7181721138 is about 1929.3433059825.

The spelling of 7181721138 in words is "seven billion, one hundred eighty-one million, seven hundred twenty-one thousand, one hundred thirty-eight".