51000081 has 16 divisors (see below), whose sum is σ = 75230208. Its totient is φ = 30472400.

The previous prime is 51000071. The next prime is 51000083. The reversal of 51000081 is 18000015.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 51000081 - 2⁵ = 51000049 is a prime.

It is a super-2 number, since 2×51000081² = 5202016524013122, which contains 22 as substring.

51000081 is a modest number, since divided by 81 gives 51 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 51000081.

It is not an unprimeable number, because it can be changed into a prime (51000083) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8541 + ... + 13226.

It is an arithmetic number, because the mean of its divisors is an integer number (4701888).

Almost surely, 2^51000081 is an apocalyptic number.

It is an amenable number.

51000081 is a deficient number, since it is larger than the sum of its proper divisors (24230127).

51000081 is a wasteful number, since it uses less digits than its factorization.

51000081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21852.

The product of its (nonzero) digits is 40, while the sum is 15.

The square root of 51000081 is about 7141.4340996749. The cubic root of 51000081 is about 370.8431732551.

Adding to 51000081 its reverse (18000015), we get a palindrome (69000096).

The spelling of 51000081 in words is "fifty-one million, eighty-one", and thus it is an aban number and an uban number.