66219721587 has 10 divisors (see below), whose sum is σ = 98920818788. Its totient is φ = 44146481004.

The previous prime is 66219721571. The next prime is 66219721649. The reversal of 66219721587 is 78512791266.

66219721587 is a `hidden beast` number, since 6 + 621 + 9 + 7 + 2 + 1 + 5 + 8 + 7 = 666.

66219721587 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 66219721587 - 2⁴ = 66219721571 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66219721187) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 408763633 + ... + 408763794.

Almost surely, 2^66219721587 is an apocalyptic number.

66219721587 is a deficient number, since it is larger than the sum of its proper divisors (32701097201).

66219721587 is an equidigital number, since it uses as much as digits as its factorization.

66219721587 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 817527439 (or 817527430 counting only the distinct ones).

The product of its digits is 2540160, while the sum is 54.

The spelling of 66219721587 in words is "sixty-six billion, two hundred nineteen million, seven hundred twenty-one thousand, five hundred eighty-seven".