66520405697 has 16 divisors (see below), whose sum is σ = 74556599040. Its totient is φ = 59042764032.

The previous prime is 66520405691. The next prime is 66520405703. The reversal of 66520405697 is 79650402566.

It is an interprime number because it is at equal distance from previous prime (66520405691) and next prime (66520405703).

It is a cyclic number.

It is not a de Polignac number, because 66520405697 - 2²⁴ = 66503628481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66520405691) 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, 1547753 + ... + 1590150.

It is an arithmetic number, because the mean of its divisors is an integer number (4659787440).

Almost surely, 2^66520405697 is an apocalyptic number.

It is an amenable number.

66520405697 is a deficient number, since it is larger than the sum of its proper divisors (8036193343).

66520405697 is a wasteful number, since it uses less digits than its factorization.

66520405697 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3137992.

The product of its (nonzero) digits is 2721600, while the sum is 50.

The spelling of 66520405697 in words is "sixty-six billion, five hundred twenty million, four hundred five thousand, six hundred ninety-seven".