7661294521 has 2 divisors, whose sum is σ = 7661294522. Its totient is φ = 7661294520.

The previous prime is 7661294519. The next prime is 7661294539. The reversal of 7661294521 is 1254921667.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7640682921 + 20611600 = 87411^2 + 4540^2 .

It is a cyclic number.

It is not a de Polignac number, because 7661294521 - 2¹ = 7661294519 is a prime.

Together with 7661294519, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (7661294021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3830647260 + 3830647261.

It is an arithmetic number, because the mean of its divisors is an integer number (3830647261).

Almost surely, 2^7661294521 is an apocalyptic number.

It is an amenable number.

7661294521 is a deficient number, since it is larger than the sum of its proper divisors (1).

7661294521 is an equidigital number, since it uses as much as digits as its factorization.

7661294521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 181440, while the sum is 43.

The square root of 7661294521 is about 87528.8210876852. The cubic root of 7661294521 is about 1971.3665628727.

The spelling of 7661294521 in words is "seven billion, six hundred sixty-one million, two hundred ninety-four thousand, five hundred twenty-one".