75129421 has 4 divisors (see below), whose sum is σ = 75170844. Its totient is φ = 75088000.

The previous prime is 75129391. The next prime is 75129433. The reversal of 75129421 is 12492157.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2368521 + 72760900 = 1539^2 + 8530^2 .

It is a cyclic number.

It is not a de Polignac number, because 75129421 - 2⁵ = 75129389 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (75129451) 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, 17860 + ... + 21661.

It is an arithmetic number, because the mean of its divisors is an integer number (18792711).

Almost surely, 2^75129421 is an apocalyptic number.

It is an amenable number.

75129421 is a deficient number, since it is larger than the sum of its proper divisors (41423).

75129421 is a wasteful number, since it uses less digits than its factorization.

75129421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41422.

The product of its digits is 5040, while the sum is 31.

The square root of 75129421 is about 8667.7229420419. The cubic root of 75129421 is about 421.9587663642.

The spelling of 75129421 in words is "seventy-five million, one hundred twenty-nine thousand, four hundred twenty-one".