756078721 has 4 divisors (see below), whose sum is σ = 756600532. Its totient is φ = 755556912.

The previous prime is 756078677. The next prime is 756078769. The reversal of 756078721 is 127870657.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 127870657 = 29 ⋅4409333.

It can be written as a sum of positive squares in 2 ways, for example, as 556252225 + 199826496 = 23585^2 + 14136^2 .

It is a cyclic number.

It is not a de Polignac number, because 756078721 - 2⁹ = 756078209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (756078121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 258726 + ... + 261631.

It is an arithmetic number, because the mean of its divisors is an integer number (189150133).

Almost surely, 2^756078721 is an apocalyptic number.

It is an amenable number.

756078721 is a deficient number, since it is larger than the sum of its proper divisors (521811).

756078721 is a wasteful number, since it uses less digits than its factorization.

756078721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 521810.

The product of its (nonzero) digits is 164640, while the sum is 43.

The square root of 756078721 is about 27496.8856600161. The cubic root of 756078721 is about 911.0083099521.

The spelling of 756078721 in words is "seven hundred fifty-six million, seventy-eight thousand, seven hundred twenty-one".