51005565 has 32 divisors (see below), whose sum is σ = 97655040. Its totient is φ = 25109568.

The previous prime is 51005561. The next prime is 51005567. The reversal of 51005565 is 56550015.

51005565 is a `hidden beast` number, since 5 + 100 + 556 + 5 = 666.

It is not a de Polignac number, because 51005565 - 2² = 51005561 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51005561) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12777 + ... + 16286.

It is an arithmetic number, because the mean of its divisors is an integer number (3051720).

Almost surely, 2^51005565 is an apocalyptic number.

It is an amenable number.

51005565 is a deficient number, since it is larger than the sum of its proper divisors (46649475).

51005565 is a wasteful number, since it uses less digits than its factorization.

51005565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29090 (or 29084 counting only the distinct ones).

The product of its (nonzero) digits is 3750, while the sum is 27.

The square root of 51005565 is about 7141.8180458480. The cubic root of 51005565 is about 370.8564649404.

The spelling of 51005565 in words is "fifty-one million, five thousand, five hundred sixty-five".