66406551 has 4 divisors (see below), whose sum is σ = 88542072. Its totient is φ = 44271032.

The previous prime is 66406541. The next prime is 66406583. The reversal of 66406551 is 15560466.

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 66406551 - 2⁵ = 66406519 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66406541) 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, 11067756 + ... + 11067761.

It is an arithmetic number, because the mean of its divisors is an integer number (22135518).

Almost surely, 2^66406551 is an apocalyptic number.

66406551 is a deficient number, since it is larger than the sum of its proper divisors (22135521).

66406551 is a wasteful number, since it uses less digits than its factorization.

66406551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22135520.

The product of its (nonzero) digits is 21600, while the sum is 33.

The square root of 66406551 is about 8149.0214749993. The cubic root of 66406551 is about 404.9520870007.

The spelling of 66406551 in words is "sixty-six million, four hundred six thousand, five hundred fifty-one".