51111440 has 20 divisors (see below), whose sum is σ = 118834284. Its totient is φ = 20444544.

The previous prime is 51111397. The next prime is 51111443. The reversal of 51111440 is 4411115.

It can be written as a sum of positive squares in 2 ways, for example, as 21864976 + 29246464 = 4676^2 + 5408^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×51111440² = 5224758597747200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (51111443) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 319367 + ... + 319526.

Almost surely, 2^51111440 is an apocalyptic number.

It is an amenable number.

51111440 is an abundant number, since it is smaller than the sum of its proper divisors (67722844).

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

51111440 is a wasteful number, since it uses less digits than its factorization.

51111440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 638906 (or 638900 counting only the distinct ones).

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

The square root of 51111440 is about 7149.2265315907. The cubic root of 51111440 is about 371.1128898472.

Adding to 51111440 its reverse (4411115), we get a palindrome (55522555).

The spelling of 51111440 in words is "fifty-one million, one hundred eleven thousand, four hundred forty".