66123551 has 32 divisors (see below), whose sum is σ = 78650880. Its totient is φ = 55085184.

The previous prime is 66123517. The next prime is 66123569. The reversal of 66123551 is 15532166.

It is not a de Polignac number, because 66123551 - 2⁶ = 66123487 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 (66123581) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 475640 + ... + 475778.

It is an arithmetic number, because the mean of its divisors is an integer number (2457840).

Almost surely, 2^66123551 is an apocalyptic number.

66123551 is a deficient number, since it is larger than the sum of its proper divisors (12527329).

66123551 is a wasteful number, since it uses less digits than its factorization.

66123551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 255.

The product of its digits is 5400, while the sum is 29.

The square root of 66123551 is about 8131.6388877028. The cubic root of 66123551 is about 404.3760162083.

The spelling of 66123551 in words is "sixty-six million, one hundred twenty-three thousand, five hundred fifty-one".