7855616521 has 2 divisors, whose sum is σ = 7855616522. Its totient is φ = 7855616520.

The previous prime is 7855616507. The next prime is 7855616567. The reversal of 7855616521 is 1256165587.

It is an a-pointer prime, because the next prime (7855616567) can be obtained adding 7855616521 to its sum of digits (46).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3986154496 + 3869462025 = 63136^2 + 62205^2 .

It is an emirp because it is prime and its reverse (1256165587) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7855616521 is a prime.

It is not a weakly prime, because it can be changed into another prime (7855614521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3927808260 + 3927808261.

It is an arithmetic number, because the mean of its divisors is an integer number (3927808261).

Almost surely, 2^7855616521 is an apocalyptic number.

It is an amenable number.

7855616521 is a deficient number, since it is larger than the sum of its proper divisors (1).

7855616521 is an equidigital number, since it uses as much as digits as its factorization.

7855616521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 504000, while the sum is 46.

The square root of 7855616521 is about 88631.9159276161. The cubic root of 7855616521 is about 1987.8949248099.

The spelling of 7855616521 in words is "seven billion, eight hundred fifty-five million, six hundred sixteen thousand, five hundred twenty-one".