51161665 has 4 divisors (see below), whose sum is σ = 61394004. Its totient is φ = 40929328.

The previous prime is 51161659. The next prime is 51161681. The reversal of 51161665 is 56616115.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56616115 = 5 ⋅11323223.

It can be written as a sum of positive squares in 2 ways, for example, as 10188864 + 40972801 = 3192^2 + 6401^2 .

It is a cyclic number.

It is not a de Polignac number, because 51161665 - 2¹¹ = 51159617 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5116162 + ... + 5116171.

It is an arithmetic number, because the mean of its divisors is an integer number (15348501).

Almost surely, 2^51161665 is an apocalyptic number.

It is an amenable number.

51161665 is a deficient number, since it is larger than the sum of its proper divisors (10232339).

51161665 is a wasteful number, since it uses less digits than its factorization.

51161665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10232338.

The product of its digits is 5400, while the sum is 31.

The square root of 51161665 is about 7152.7382868381. The cubic root of 51161665 is about 371.2344089104.

The spelling of 51161665 in words is "fifty-one million, one hundred sixty-one thousand, six hundred sixty-five".