66213067761 has 15 divisors (see below), whose sum is σ = 98914338633. Its totient is φ = 44140501260.

The previous prime is 66213067709. The next prime is 66213067777. The reversal of 66213067761 is 16776031266.

The square root of 66213067761 is 257319.

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

It is not a de Polignac number, because 66213067761 - 2³¹ = 64065584113 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66213067561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 2301576 + ... + 2330166.

Almost surely, 2^66213067761 is an apocalyptic number.

66213067761 is the 257319-th square number.

66213067761 is the 128660-th centered octagonal number.

It is an amenable number.

66213067761 is a deficient number, since it is larger than the sum of its proper divisors (32701270872).

66213067761 is an frugal number, since it uses more digits than its factorization.

66213067761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57194 (or 28594 counting only the distinct ones).

The product of its (nonzero) digits is 381024, while the sum is 45.

The spelling of 66213067761 in words is "sixty-six billion, two hundred thirteen million, sixty-seven thousand, seven hundred sixty-one".