51387581 has 8 divisors (see below), whose sum is σ = 59837184. Its totient is φ = 43215120.

The previous prime is 51387563. The next prime is 51387587. The reversal of 51387581 is 18578315.

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

It is a cyclic number.

It is not a de Polignac number, because 51387581 - 2⁶ = 51387517 is a prime.

It is a super-3 number, since 3×51387581³ (a number of 24 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51387587) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 68885 + ... + 69626.

It is an arithmetic number, because the mean of its divisors is an integer number (7479648).

Almost surely, 2^51387581 is an apocalyptic number.

It is an amenable number.

51387581 is a deficient number, since it is larger than the sum of its proper divisors (8449603).

51387581 is a wasteful number, since it uses less digits than its factorization.

51387581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138571.

The product of its digits is 33600, while the sum is 38.

The square root of 51387581 is about 7168.5131652247. The cubic root of 51387581 is about 371.7800299914.

The spelling of 51387581 in words is "fifty-one million, three hundred eighty-seven thousand, five hundred eighty-one".