75766721 has 2 divisors, whose sum is σ = 75766722. Its totient is φ = 75766720.

The previous prime is 75766693. The next prime is 75766723. The reversal of 75766721 is 12766757.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 50566321 + 25200400 = 7111^2 + 5020^2 .

It is a cyclic number.

It is not a de Polignac number, because 75766721 - 2⁶ = 75766657 is a prime.

It is a super-2 number, since 2×75766721² = 11481192022183682, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 75766723, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (75766723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 37883360 + 37883361.

It is an arithmetic number, because the mean of its divisors is an integer number (37883361).

Almost surely, 2^75766721 is an apocalyptic number.

It is an amenable number.

75766721 is a deficient number, since it is larger than the sum of its proper divisors (1).

75766721 is an equidigital number, since it uses as much as digits as its factorization.

75766721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 123480, while the sum is 41.

The square root of 75766721 is about 8704.4081361113. The cubic root of 75766721 is about 423.1485244672.

The spelling of 75766721 in words is "seventy-five million, seven hundred sixty-six thousand, seven hundred twenty-one".