51987581 has 8 divisors (see below), whose sum is σ = 55187640. Its totient is φ = 48803328.

The previous prime is 51987569. The next prime is 51987587. The reversal of 51987581 is 18578915.

It is a happy number.

51987581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 40119556 + 11868025 = 6334^2 + 3445^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-51987581 is a prime.

It is a super-2 number, since 2×51987581² = 5405417156463122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51987587) 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 7 ways as a sum of consecutive naturals, for example, 3215 + ... + 10691.

It is an arithmetic number, because the mean of its divisors is an integer number (6898455).

Almost surely, 2^51987581 is an apocalyptic number.

It is an amenable number.

51987581 is a deficient number, since it is larger than the sum of its proper divisors (3200059).

51987581 is a wasteful number, since it uses less digits than its factorization.

51987581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7903.

The product of its digits is 100800, while the sum is 44.

The square root of 51987581 is about 7210.2413967911. The cubic root of 51987581 is about 373.2213991774.

The spelling of 51987581 in words is "fifty-one million, nine hundred eighty-seven thousand, five hundred eighty-one".