66521879 has 4 divisors (see below), whose sum is σ = 66618840. Its totient is φ = 66424920.

The previous prime is 66521863. The next prime is 66521887. The reversal of 66521879 is 97812566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 97812566 = 2 ⋅48906283.

It is a cyclic number.

It is not a de Polignac number, because 66521879 - 2⁴ = 66521863 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66520879) 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, 47444 + ... + 48825.

It is an arithmetic number, because the mean of its divisors is an integer number (16654710).

Almost surely, 2^66521879 is an apocalyptic number.

66521879 is a deficient number, since it is larger than the sum of its proper divisors (96961).

66521879 is an equidigital number, since it uses as much as digits as its factorization.

66521879 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96960.

The product of its digits is 181440, while the sum is 44.

The square root of 66521879 is about 8156.0945923892. The cubic root of 66521879 is about 405.1863776630.

The spelling of 66521879 in words is "sixty-six million, five hundred twenty-one thousand, eight hundred seventy-nine".