66909781543 has 4 divisors (see below), whose sum is σ = 72992488968. Its totient is φ = 60827074120.

The previous prime is 66909781541. The next prime is 66909781553. The reversal of 66909781543 is 34518790966.

66909781543 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66909781543 - 2¹ = 66909781541 is a prime.

It is a super-2 number, since 2×66909781543² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66909781541) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3041353696 + ... + 3041353717.

It is an arithmetic number, because the mean of its divisors is an integer number (18248122242).

Almost surely, 2^66909781543 is an apocalyptic number.

66909781543 is a deficient number, since it is larger than the sum of its proper divisors (6082707425).

66909781543 is a wasteful number, since it uses less digits than its factorization.

66909781543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6082707424.

The product of its (nonzero) digits is 9797760, while the sum is 58.

The spelling of 66909781543 in words is "sixty-six billion, nine hundred nine million, seven hundred eighty-one thousand, five hundred forty-three".