51605513 has 4 divisors (see below), whose sum is σ = 51722448. Its totient is φ = 51488580.

The previous prime is 51605503. The next prime is 51605527. The reversal of 51605513 is 31550615.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 31550615 = 5 ⋅6310123.

It is a cyclic number.

It is not a de Polignac number, because 51605513 - 2⁴ = 51605497 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (51605503) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 57803 + ... + 58688.

It is an arithmetic number, because the mean of its divisors is an integer number (12930612).

Almost surely, 2^51605513 is an apocalyptic number.

It is an amenable number.

51605513 is a deficient number, since it is larger than the sum of its proper divisors (116935).

51605513 is a wasteful number, since it uses less digits than its factorization.

51605513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116934.

The product of its (nonzero) digits is 2250, while the sum is 26.

The square root of 51605513 is about 7183.6977247097. The cubic root of 51605513 is about 372.3048552200.

The spelling of 51605513 in words is "fifty-one million, six hundred five thousand, five hundred thirteen".