7744815661 has 12 divisors (see below), whose sum is σ = 8806448700. Its totient is φ = 6797954240.

The previous prime is 7744815649. The next prime is 7744815671. The reversal of 7744815661 is 1665184477.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 6039621225 + 1705194436 = 77715^2 + 41294^2 .

It is not a de Polignac number, because 7744815661 - 2⁵ = 7744815629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7744815671) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1100056 + ... + 1107073.

It is an arithmetic number, because the mean of its divisors is an integer number (733870725).

Almost surely, 2^7744815661 is an apocalyptic number.

It is an amenable number.

7744815661 is a deficient number, since it is larger than the sum of its proper divisors (1061633039).

7744815661 is a wasteful number, since it uses less digits than its factorization.

7744815661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2207180 (or 2207169 counting only the distinct ones).

The product of its digits is 1128960, while the sum is 49.

The square root of 7744815661 is about 88004.6343154723. The cubic root of 7744815661 is about 1978.5044364764.

The spelling of 7744815661 in words is "seven billion, seven hundred forty-four million, eight hundred fifteen thousand, six hundred sixty-one".