66820699009 has 9 divisors (see below), whose sum is σ = 69858477633. Its totient is φ = 63909764292.

The previous prime is 66820698977. The next prime is 66820699013. The reversal of 66820699009 is 90099602866.

The square root of 66820699009 is 258497.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 66820699009 - 2⁵ = 66820698977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66820639009) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 5939812 + ... + 5951050.

Almost surely, 2^66820699009 is an apocalyptic number.

66820699009 is the 258497-th square number.

66820699009 is the 129249-th centered octagonal number.

It is an amenable number.

66820699009 is a deficient number, since it is larger than the sum of its proper divisors (3037778624).

66820699009 is an frugal number, since it uses more digits than its factorization.

66820699009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22524 (or 11262 counting only the distinct ones).

The product of its (nonzero) digits is 2519424, while the sum is 55.

The spelling of 66820699009 in words is "sixty-six billion, eight hundred twenty million, six hundred ninety-nine thousand, nine".