7721918791 has 2 divisors, whose sum is σ = 7721918792. Its totient is φ = 7721918790.

The previous prime is 7721918779. The next prime is 7721918797. The reversal of 7721918791 is 1978191277.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 7721918791 - 2⁷ = 7721918663 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7721918797) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3860959395 + 3860959396.

It is an arithmetic number, because the mean of its divisors is an integer number (3860959396).

Almost surely, 2^7721918791 is an apocalyptic number.

7721918791 is a deficient number, since it is larger than the sum of its proper divisors (1).

7721918791 is an equidigital number, since it uses as much as digits as its factorization.

7721918791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 444528, while the sum is 52.

The square root of 7721918791 is about 87874.4490224548. The cubic root of 7721918791 is about 1976.5527534540.

The spelling of 7721918791 in words is "seven billion, seven hundred twenty-one million, nine hundred eighteen thousand, seven hundred ninety-one".