51987309 has 16 divisors (see below), whose sum is σ = 80066880. Its totient is φ = 29653760.

The previous prime is 51987281. The next prime is 51987347. The reversal of 51987309 is 90378915.

It is a happy number.

51987309 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 51987309 - 2⁵ = 51987277 is a prime.

It is a super-2 number, since 2×51987309² = 5405360594122962, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51987349) 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 15 ways as a sum of consecutive naturals, for example, 45774 + ... + 46895.

It is an arithmetic number, because the mean of its divisors is an integer number (5004180).

Almost surely, 2^51987309 is an apocalyptic number.

It is an amenable number.

51987309 is a deficient number, since it is larger than the sum of its proper divisors (28079571).

51987309 is a wasteful number, since it uses less digits than its factorization.

51987309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92700.

The product of its (nonzero) digits is 68040, while the sum is 42.

The square root of 51987309 is about 7210.2225347072. Note that the first 3 decimals coincide. The cubic root of 51987309 is about 373.2207482758.

The spelling of 51987309 in words is "fifty-one million, nine hundred eighty-seven thousand, three hundred nine".