51438943665 has 12 divisors (see below), whose sum is σ = 89160835764. Its totient is φ = 27434103264.

The previous prime is 51438943663. The next prime is 51438943667. The reversal of 51438943665 is 56634983415.

51438943665 is a `hidden beast` number, since 5 + 143 + 8 + 9 + 436 + 65 = 666.

It is an interprime number because it is at equal distance from previous prime (51438943663) and next prime (51438943667).

It can be written as a sum of positive squares in 2 ways, for example, as 20992532544 + 30446411121 = 144888^2 + 174489^2 .

It is not a de Polignac number, because 51438943665 - 2¹ = 51438943663 is a prime.

It is not an unprimeable number, because it can be changed into a prime (51438943663) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 571543774 + ... + 571543863.

It is an arithmetic number, because the mean of its divisors is an integer number (7430069647).

Almost surely, 2^51438943665 is an apocalyptic number.

It is an amenable number.

51438943665 is a deficient number, since it is larger than the sum of its proper divisors (37721892099).

51438943665 is a wasteful number, since it uses less digits than its factorization.

51438943665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1143087648 (or 1143087645 counting only the distinct ones).

The product of its digits is 9331200, while the sum is 54.

The spelling of 51438943665 in words is "fifty-one billion, four hundred thirty-eight million, nine hundred forty-three thousand, six hundred sixty-five".