51520405 has 4 divisors (see below), whose sum is σ = 61824492. Its totient is φ = 41216320.

The previous prime is 51520379. The next prime is 51520411. The reversal of 51520405 is 50402515.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50402515 = 5 ⋅10080503.

It can be written as a sum of positive squares in 2 ways, for example, as 40170244 + 11350161 = 6338^2 + 3369^2 .

It is not a de Polignac number, because 51520405 - 2⁵ = 51520373 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

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 3 ways as a sum of consecutive naturals, for example, 5152036 + ... + 5152045.

It is an arithmetic number, because the mean of its divisors is an integer number (15456123).

Almost surely, 2^51520405 is an apocalyptic number.

It is an amenable number.

51520405 is a deficient number, since it is larger than the sum of its proper divisors (10304087).

51520405 is a wasteful number, since it uses less digits than its factorization.

51520405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10304086.

The product of its (nonzero) digits is 1000, while the sum is 22.

The square root of 51520405 is about 7177.7715901246. The cubic root of 51520405 is about 372.1000737622.

The spelling of 51520405 in words is "fifty-one million, five hundred twenty thousand, four hundred five".