70728121 has 4 divisors (see below), whose sum is σ = 70816144. Its totient is φ = 70640100.

The previous prime is 70728113. The next prime is 70728173. The reversal of 70728121 is 12182707.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 70728121 - 2³ = 70728113 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 70728121.

It is not an unprimeable number, because it can be changed into a prime (70728191) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 42795 + ... + 44416.

It is an arithmetic number, because the mean of its divisors is an integer number (17704036).

It is a Poulet number, since it divides 2^70728120-1.

Almost surely, 2^70728121 is an apocalyptic number.

It is an amenable number.

70728121 is a deficient number, since it is larger than the sum of its proper divisors (88023).

70728121 is an equidigital number, since it uses as much as digits as its factorization.

70728121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88022.

The product of its (nonzero) digits is 1568, while the sum is 28.

The square root of 70728121 is about 8410.0012485136. The cubic root of 70728121 is about 413.5525536008.

The spelling of 70728121 in words is "seventy million, seven hundred twenty-eight thousand, one hundred twenty-one".