66561666015 has 32 divisors (see below), whose sum is σ = 115762784256. Its totient is φ = 32462559360.

The previous prime is 66561666011. The next prime is 66561666019. The reversal of 66561666015 is 51066616566.

It is an interprime number because it is at equal distance from previous prime (66561666011) and next prime (66561666019).

It is not a de Polignac number, because 66561666015 - 2² = 66561666011 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66561666011) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1574191 + ... + 1615920.

It is an arithmetic number, because the mean of its divisors is an integer number (3617587008).

Almost surely, 2^66561666015 is an apocalyptic number.

66561666015 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

66561666015 is a deficient number, since it is larger than the sum of its proper divisors (49201118241).

66561666015 is a wasteful number, since it uses less digits than its factorization.

66561666015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3190239.

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

The spelling of 66561666015 in words is "sixty-six billion, five hundred sixty-one million, six hundred sixty-six thousand, fifteen".