66406511 has 4 divisors (see below), whose sum is σ = 68026224. Its totient is φ = 64786800.

The previous prime is 66406493. The next prime is 66406517. The reversal of 66406511 is 11560466.

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 66406511 - 2¹⁸ = 66144367 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 (66406517) 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, 809795 + ... + 809876.

It is an arithmetic number, because the mean of its divisors is an integer number (17006556).

Almost surely, 2^66406511 is an apocalyptic number.

66406511 is a deficient number, since it is larger than the sum of its proper divisors (1619713).

66406511 is a wasteful number, since it uses less digits than its factorization.

66406511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1619712.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 66406511 is about 8149.0190207165. The cubic root of 66406511 is about 404.9520056931.

Adding to 66406511 its reverse (11560466), we get a palindrome (77966977).

The spelling of 66406511 in words is "sixty-six million, four hundred six thousand, five hundred eleven".