7647121907649 has 81 divisors (see below), whose sum is σ = 13209620036067. Its totient is φ = 4250487050208.

The previous prime is 7647121907647. The next prime is 7647121907653. The reversal of 7647121907649 is 9467091217467.

The square root of 7647121907649 is 2765343.

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

7647121907649 is a `hidden beast` number, since 7 + 6 + 471 + 2 + 1 + 90 + 76 + 4 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 6842749698225 + 804372209424 = 2615865^2 + 896868^2 .

It is not a de Polignac number, because 7647121907649 - 2¹ = 7647121907647 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (7647121907647) 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, 2148669732 + ... + 2148673290.

Almost surely, 2^{7647121907649} is an apocalyptic number.

7647121907649 is the 2765343-rd square number.

7647121907649 is the 1382672-nd centered octagonal number.

It is an amenable number.

7647121907649 is a deficient number, since it is larger than the sum of its proper divisors (5562498128418).

7647121907649 is an frugal number, since it uses more digits than its factorization.

7647121907649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7212 (or 3606 counting only the distinct ones).

The product of its (nonzero) digits is 32006016, while the sum is 63.

The spelling of 7647121907649 in words is "seven trillion, six hundred forty-seven billion, one hundred twenty-one million, nine hundred seven thousand, six hundred forty-nine".