51605340515621 has 8 divisors (see below), whose sum is σ = 52079539357560. Its totient is φ = 51131155407552.

The previous prime is 51605340515587. The next prime is 51605340515633. The reversal of 51605340515621 is 12651504350615.

It can be written as a sum of positive squares in 4 ways, for example, as 17127140865025 + 34478199650596 = 4138495^2 + 5871814^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51605340515621 is a prime.

It is a super-2 number, since 2×51605340515621² (a number of 28 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51605340514621) 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, 4193591 + ... + 10990763.

It is an arithmetic number, because the mean of its divisors is an integer number (6509942419695).

Almost surely, 2^{51605340515621} is an apocalyptic number.

It is an amenable number.

51605340515621 is a deficient number, since it is larger than the sum of its proper divisors (474198841939).

51605340515621 is a wasteful number, since it uses less digits than its factorization.

51605340515621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6866935.

The product of its (nonzero) digits is 540000, while the sum is 44.

The spelling of 51605340515621 in words is "fifty-one trillion, six hundred five billion, three hundred forty million, five hundred fifteen thousand, six hundred twenty-one".