51281000 has 64 divisors (see below), whose sum is σ = 126360000. Its totient is φ = 19425600.

The previous prime is 51280987. The next prime is 51281003. The reversal of 51281000 is 18215.

51281000 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×51281000² = 5259481922000000, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 51281000.

It is not an unprimeable number, because it can be changed into a prime (51281003) 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, 17651 + ... + 20349.

It is an arithmetic number, because the mean of its divisors is an integer number (1974375).

Almost surely, 2^51281000 is an apocalyptic number.

51281000 is a gapful number since it is divisible by the number (50) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51281000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (63180000).

51281000 is an abundant number, since it is smaller than the sum of its proper divisors (75079000).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51281000 is a wasteful number, since it uses less digits than its factorization.

51281000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2739 (or 2725 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 17.

The square root of 51281000 is about 7161.0753382436. The cubic root of 51281000 is about 371.5228205457.

Adding to 51281000 its reverse (18215), we get a palindrome (51299215).

The spelling of 51281000 in words is "fifty-one million, two hundred eighty-one thousand".