7745457821 has 2 divisors, whose sum is σ = 7745457822. Its totient is φ = 7745457820.

The previous prime is 7745457793. The next prime is 7745457823. The reversal of 7745457821 is 1287545477.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7518624100 + 226833721 = 86710^2 + 15061^2 .

It is an emirp because it is prime and its reverse (1287545477) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 7745457821 - 2¹⁴ = 7745441437 is a prime.

Together with 7745457823, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 7745457821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7745457823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3872728910 + 3872728911.

It is an arithmetic number, because the mean of its divisors is an integer number (3872728911).

Almost surely, 2^7745457821 is an apocalyptic number.

It is an amenable number.

7745457821 is a deficient number, since it is larger than the sum of its proper divisors (1).

7745457821 is an equidigital number, since it uses as much as digits as its factorization.

7745457821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2195200, while the sum is 50.

The square root of 7745457821 is about 88008.2826840747. The cubic root of 7745457821 is about 1978.5591174118.

The spelling of 7745457821 in words is "seven billion, seven hundred forty-five million, four hundred fifty-seven thousand, eight hundred twenty-one".