66661543 has 12 divisors (see below), whose sum is σ = 73112160. Its totient is φ = 60742656.

The previous prime is 66661541. The next prime is 66661547. The reversal of 66661543 is 34516666.

It is not a de Polignac number, because 66661543 - 2¹ = 66661541 is a prime.

It is a super-2 number, since 2×66661543² = 8887522630281698, which 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 (66661541) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10855 + ... + 15847.

It is an arithmetic number, because the mean of its divisors is an integer number (6092680).

Almost surely, 2^66661543 is an apocalyptic number.

66661543 is a deficient number, since it is larger than the sum of its proper divisors (6450617).

66661543 is a wasteful number, since it uses less digits than its factorization.

66661543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5098 (or 5085 counting only the distinct ones).

The product of its digits is 77760, while the sum is 37.

The square root of 66661543 is about 8164.6520440249. The cubic root of 66661543 is about 405.4697450469.

The spelling of 66661543 in words is "sixty-six million, six hundred sixty-one thousand, five hundred forty-three".