75007721 has 4 divisors (see below), whose sum is σ = 75026244. Its totient is φ = 74989200.

The previous prime is 75007697. The next prime is 75007727. The reversal of 75007721 is 12770057.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12770057 = 2089 ⋅6113.

It can be written as a sum of positive squares in 2 ways, for example, as 29593600 + 45414121 = 5440^2 + 6739^2 .

It is a cyclic number.

It is not a de Polignac number, because 75007721 - 2⁶ = 75007657 is a prime.

It is a super-2 number, since 2×75007721² = 11252316419227682, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (75007727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 290 + ... + 12251.

It is an arithmetic number, because the mean of its divisors is an integer number (18756561).

Almost surely, 2^75007721 is an apocalyptic number.

It is an amenable number.

75007721 is a deficient number, since it is larger than the sum of its proper divisors (18523).

75007721 is a wasteful number, since it uses less digits than its factorization.

75007721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18522.

The product of its (nonzero) digits is 3430, while the sum is 29.

The square root of 75007721 is about 8660.6997985151. The cubic root of 75007721 is about 421.7308035845.

Adding to 75007721 its reverse (12770057), we get a palindrome (87777778).

The spelling of 75007721 in words is "seventy-five million, seven thousand, seven hundred twenty-one".