12381720538 has 16 divisors (see below), whose sum is σ = 21327366240. Its totient is φ = 5331841200.

The previous prime is 12381720529. The next prime is 12381720539. The reversal of 12381720538 is 83502718321.

It is a happy number.

It is a super-2 number, since 2×12381720538² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 12381720538.

It is not an unprimeable number, because it can be changed into a prime (12381720539) 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, 14810253 + ... + 14811088.

It is an arithmetic number, because the mean of its divisors is an integer number (1332960390).

Almost surely, 2^12381720538 is an apocalyptic number.

12381720538 is a deficient number, since it is larger than the sum of its proper divisors (8945645702).

12381720538 is a wasteful number, since it uses less digits than its factorization.

12381720538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29621373.

The product of its (nonzero) digits is 80640, while the sum is 40.

The spelling of 12381720538 in words is "twelve billion, three hundred eighty-one million, seven hundred twenty thousand, five hundred thirty-eight".