66131061555065 has 16 divisors (see below), whose sum is σ = 85496237653008. Its totient is φ = 48815497967616.

The previous prime is 66131061555043. The next prime is 66131061555067. The reversal of 66131061555065 is 56055516013166.

It can be written as a sum of positive squares in 8 ways, for example, as 14003282473216 + 52127779081849 = 3742096^2 + 7219957^2 .

It is a cyclic number.

It is not a de Polignac number, because 66131061555065 - 2³² = 66126766587769 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66131061555067) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 205541024 + ... + 205862513.

It is an arithmetic number, because the mean of its divisors is an integer number (5343514853313).

Almost surely, 2^{66131061555065} is an apocalyptic number.

66131061555065 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

66131061555065 is a deficient number, since it is larger than the sum of its proper divisors (19365176097943).

66131061555065 is a wasteful number, since it uses less digits than its factorization.

66131061555065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 411406028.

The product of its (nonzero) digits is 2430000, while the sum is 50.

The spelling of 66131061555065 in words is "sixty-six trillion, one hundred thirty-one billion, sixty-one million, five hundred fifty-five thousand, sixty-five".