66542121 has 8 divisors (see below), whose sum is σ = 98580960. Its totient is φ = 44361396.

The previous prime is 66542111. The next prime is 66542129. The reversal of 66542121 is 12124566.

66542121 is a `hidden beast` number, since 6 + 654 + 2 + 1 + 2 + 1 = 666.

It is not a de Polignac number, because 66542121 - 2¹⁴ = 66525737 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 2464523 = 66542121 / (6 + 6 + 5 + 4 + 2 + 1 + 2 + 1).

It is not an unprimeable number, because it can be changed into a prime (66542129) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1232235 + ... + 1232288.

It is an arithmetic number, because the mean of its divisors is an integer number (12322620).

Almost surely, 2^66542121 is an apocalyptic number.

It is an amenable number.

66542121 is a deficient number, since it is larger than the sum of its proper divisors (32038839).

66542121 is a wasteful number, since it uses less digits than its factorization.

66542121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2464532 (or 2464526 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 66542121 is about 8157.3354105369. The cubic root of 66542121 is about 405.2274716660.

Adding to 66542121 its reverse (12124566), we get a palindrome (78666687).

The spelling of 66542121 in words is "sixty-six million, five hundred forty-two thousand, one hundred twenty-one".