51121686 has 128 divisors (see below), whose sum is σ = 141336576. Its totient is φ = 11911680.

The previous prime is 51121657. The next prime is 51121717. The reversal of 51121686 is 68612115.

It is a super-2 number, since 2×51121686² = 5226853558965192, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 180501 + ... + 180783.

It is an arithmetic number, because the mean of its divisors is an integer number (1104192).

Almost surely, 2^51121686 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51121686, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (70668288).

51121686 is an abundant number, since it is smaller than the sum of its proper divisors (90214890).

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

51121686 is a wasteful number, since it uses less digits than its factorization.

51121686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 346.

The product of its digits is 2880, while the sum is 30.

The square root of 51121686 is about 7149.9430766965. The cubic root of 51121686 is about 371.1376864394.

The spelling of 51121686 in words is "fifty-one million, one hundred twenty-one thousand, six hundred eighty-six".