66081406857521 has 12 divisors (see below), whose sum is σ = 72635266951632. Its totient is φ = 60073731531000.

The previous prime is 66081406857491. The next prime is 66081406857541. The reversal of 66081406857521 is 12575860418066.

It is not a de Polignac number, because 66081406857521 - 2¹⁴ = 66081406841137 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66081406857541) 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, 28175126 + ... + 30430256.

It is an arithmetic number, because the mean of its divisors is an integer number (6052938912636).

Almost surely, 2^{66081406857521} is an apocalyptic number.

It is an amenable number.

66081406857521 is a deficient number, since it is larger than the sum of its proper divisors (6553860094111).

66081406857521 is a wasteful number, since it uses less digits than its factorization.

66081406857521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2497324 (or 2497313 counting only the distinct ones).

The product of its (nonzero) digits is 19353600, while the sum is 59.

The spelling of 66081406857521 in words is "sixty-six trillion, eighty-one billion, four hundred six million, eight hundred fifty-seven thousand, five hundred twenty-one".