66521646575 has 12 divisors (see below), whose sum is σ = 82529618808. Its totient is φ = 53189719200.

The previous prime is 66521646553. The next prime is 66521646589. The reversal of 66521646575 is 57564612566.

It is not a de Polignac number, because 66521646575 - 2¹² = 66521642479 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 640712 + ... + 737261.

It is an arithmetic number, because the mean of its divisors is an integer number (6877468234).

Almost surely, 2^66521646575 is an apocalyptic number.

66521646575 is a deficient number, since it is larger than the sum of its proper divisors (16007972233).

66521646575 is a wasteful number, since it uses less digits than its factorization.

66521646575 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1379914 (or 1379909 counting only the distinct ones).

The product of its digits is 9072000, while the sum is 53.

The spelling of 66521646575 in words is "sixty-six billion, five hundred twenty-one million, six hundred forty-six thousand, five hundred seventy-five".