51987691 has 16 divisors (see below), whose sum is σ = 62346240. Its totient is φ = 42406560.

The previous prime is 51987679. The next prime is 51987707. The reversal of 51987691 is 19678915.

It is a happy number.

51987691 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 51987691 - 2⁷ = 51987563 is a prime.

It is a super-2 number, since 2×51987691² = 5405440031022962, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51987641) 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, 12610 + ... + 16216.

It is an arithmetic number, because the mean of its divisors is an integer number (3896640).

Almost surely, 2^51987691 is an apocalyptic number.

51987691 is a deficient number, since it is larger than the sum of its proper divisors (10358549).

51987691 is a wasteful number, since it uses less digits than its factorization.

51987691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3714.

The product of its digits is 136080, while the sum is 46.

The square root of 51987691 is about 7210.2490248257. The cubic root of 51987691 is about 373.2216624090.

The spelling of 51987691 in words is "fifty-one million, nine hundred eighty-seven thousand, six hundred ninety-one".