51121440 has 144 divisors (see below), whose sum is σ = 176432256. Its totient is φ = 13478400.

The previous prime is 51121439. The next prime is 51121451. The reversal of 51121440 is 4412115.

It is a tau number, because it is divible by the number of its divisors (144).

It is a super-2 number, since 2×51121440² = 5226803255347200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 188505 + ... + 188775.

It is an arithmetic number, because the mean of its divisors is an integer number (1225224).

Almost surely, 2^51121440 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51121440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88216128).

51121440 is an abundant number, since it is smaller than the sum of its proper divisors (125310816).

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

51121440 is a wasteful number, since it uses less digits than its factorization.

51121440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 423 (or 412 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 51121440 is about 7149.9258737416. The cubic root of 51121440 is about 371.1370911277.

Adding to 51121440 its reverse (4412115), we get a palindrome (55533555).

It can be divided in two parts, 51 and 121440, that multiplied together give a triangular number (6193440 = T₃₅₁₉).

The spelling of 51121440 in words is "fifty-one million, one hundred twenty-one thousand, four hundred forty".