66400521 has 16 divisors (see below), whose sum is σ = 102264768. Its totient is φ = 37875200.

The previous prime is 66400493. The next prime is 66400567. The reversal of 66400521 is 12500466.

66400521 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 66400521 - 2⁵ = 66400489 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 66400491 and 66400500.

It is not an unprimeable number, because it can be changed into a prime (66400571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 58620 + ... + 59741.

It is an arithmetic number, because the mean of its divisors is an integer number (6391548).

Almost surely, 2^66400521 is an apocalyptic number.

It is an amenable number.

66400521 is a deficient number, since it is larger than the sum of its proper divisors (35864247).

66400521 is a wasteful number, since it uses less digits than its factorization.

66400521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118392.

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 66400521 is about 8148.6514835278. The cubic root of 66400521 is about 404.9398295002.

Adding to 66400521 its reverse (12500466), we get a palindrome (78900987).

The spelling of 66400521 in words is "sixty-six million, four hundred thousand, five hundred twenty-one".