51861000 has 128 divisors (see below), whose sum is σ = 165110400. Its totient is φ = 13548800.

The previous prime is 51860993. The next prime is 51861037. The reversal of 51861000 is 16815.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 176854 + ... + 177146.

It is an arithmetic number, because the mean of its divisors is an integer number (1289925).

Almost surely, 2^51861000 is an apocalyptic number.

51861000 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 51861000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (82555200).

51861000 is an abundant number, since it is smaller than the sum of its proper divisors (113249400).

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

51861000 is a wasteful number, since it uses less digits than its factorization.

51861000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 376 (or 362 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 21.

The square root of 51861000 is about 7201.4581856732. The cubic root of 51861000 is about 372.9182425922.

Adding to 51861000 its reverse (16815), we get a palindrome (51877815).

The spelling of 51861000 in words is "fifty-one million, eight hundred sixty-one thousand".