12155724009 has 81 divisors (see below), whose sum is σ = 20979998949. Its totient is φ = 6773944320.

The previous prime is 12155724001. The next prime is 12155724019. The reversal of 12155724009 is 90042755121.

The square root of 12155724009 is 110253.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 864536409 + 11291187600 = 29403^2 + 106260^2 .

It is not a de Polignac number, because 12155724009 - 2³ = 12155724001 is a prime.

It is not an unprimeable number, because it can be changed into a prime (12155724001) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 47298409 + ... + 47298665.

Almost surely, 2^12155724009 is an apocalyptic number.

12155724009 is the 110253-rd square number.

12155724009 is the 55127-th centered octagonal number.

It is an amenable number.

12155724009 is a deficient number, since it is larger than the sum of its proper divisors (8824274940).

12155724009 is a wasteful number, since it uses less digits than its factorization.

12155724009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 568 (or 284 counting only the distinct ones).

The product of its (nonzero) digits is 25200, while the sum is 36.

Multiplying 12155724009 by its sum of digits (36), we get a square (437606064324 = 661518²).

It can be divided in two parts, 12155 and 724009, that added together give a square (736164 = 858²).

The spelling of 12155724009 in words is "twelve billion, one hundred fifty-five million, seven hundred twenty-four thousand, nine".