51556665565 has 8 divisors (see below), whose sum is σ = 64557911808. Its totient is φ = 39452057040.

The previous prime is 51556665499. The next prime is 51556665569. The reversal of 51556665565 is 56556665515.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 51556665565 - 2³¹ = 49409181917 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51556665569) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 224159301 + ... + 224159530.

It is an arithmetic number, because the mean of its divisors is an integer number (8069738976).

Almost surely, 2^51556665565 is an apocalyptic number.

It is an amenable number.

51556665565 is a deficient number, since it is larger than the sum of its proper divisors (13001246243).

51556665565 is a wasteful number, since it uses less digits than its factorization.

51556665565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 448318859.

The product of its digits is 20250000, while the sum is 55.

The spelling of 51556665565 in words is "fifty-one billion, five hundred fifty-six million, six hundred sixty-five thousand, five hundred sixty-five".