51405551 has 4 divisors (see below), whose sum is σ = 51780912. Its totient is φ = 51030192.

The previous prime is 51405539. The next prime is 51405577. The reversal of 51405551 is 15550415.

51405551 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 51405551 - 2¹⁰ = 51404527 is a prime.

It is a super-2 number, since 2×51405551² = 5285061347227202, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 51405551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51405521) 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 3 ways as a sum of consecutive naturals, for example, 187475 + ... + 187748.

It is an arithmetic number, because the mean of its divisors is an integer number (12945228).

Almost surely, 2^51405551 is an apocalyptic number.

51405551 is a deficient number, since it is larger than the sum of its proper divisors (375361).

51405551 is a wasteful number, since it uses less digits than its factorization.

51405551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 375360.

The product of its (nonzero) digits is 2500, while the sum is 26.

The square root of 51405551 is about 7169.7664536580. The cubic root of 51405551 is about 371.8233615279.

Adding to 51405551 its reverse (15550415), we get a palindrome (66955966).

The spelling of 51405551 in words is "fifty-one million, four hundred five thousand, five hundred fifty-one".