66661016565 has 96 divisors (see below), whose sum is σ = 127245375360. Its totient is φ = 29537664000.

The previous prime is 66661016551. The next prime is 66661016567. The reversal of 66661016565 is 56561016666.

It is not a de Polignac number, because 66661016565 - 2⁹ = 66661016053 is a prime.

It is a super-2 number, since 2×66661016565² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66661016567) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 2804551 + ... + 2828219.

It is an arithmetic number, because the mean of its divisors is an integer number (1325472660).

Almost surely, 2^66661016565 is an apocalyptic number.

66661016565 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

66661016565 is a deficient number, since it is larger than the sum of its proper divisors (60584358795).

66661016565 is a wasteful number, since it uses less digits than its factorization.

66661016565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23815 (or 23802 counting only the distinct ones).

The product of its (nonzero) digits is 1166400, while the sum is 48.

The spelling of 66661016565 in words is "sixty-six billion, six hundred sixty-one million, sixteen thousand, five hundred sixty-five".