51188721 has 4 divisors (see below), whose sum is σ = 68251632. Its totient is φ = 34125812.

The previous prime is 51188713. The next prime is 51188729. The reversal of 51188721 is 12788115.

51188721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 an interprime number because it is at equal distance from previous prime (51188713) and next prime (51188729).

It is a cyclic number.

It is not a de Polignac number, because 51188721 - 2³ = 51188713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (51188729) 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, 8531451 + ... + 8531456.

It is an arithmetic number, because the mean of its divisors is an integer number (17062908).

Almost surely, 2^51188721 is an apocalyptic number.

It is an amenable number.

51188721 is a deficient number, since it is larger than the sum of its proper divisors (17062911).

51188721 is a wasteful number, since it uses less digits than its factorization.

51188721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17062910.

The product of its digits is 4480, while the sum is 33.

The square root of 51188721 is about 7154.6293405040. The cubic root of 51188721 is about 371.2998377696.

The spelling of 51188721 in words is "fifty-one million, one hundred eighty-eight thousand, seven hundred twenty-one".