66810155 has 4 divisors (see below), whose sum is σ = 80172192. Its totient is φ = 53448120.

The previous prime is 66810143. The next prime is 66810169. The reversal of 66810155 is 55101866.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 55101866 = 2 ⋅27550933.

It is not a de Polignac number, because 66810155 - 2⁶ = 66810091 is a prime.

It is a super-2 number, since 2×66810155² = 8927193622248050, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6681011 + ... + 6681020.

It is an arithmetic number, because the mean of its divisors is an integer number (20043048).

Almost surely, 2^66810155 is an apocalyptic number.

66810155 is a deficient number, since it is larger than the sum of its proper divisors (13362037).

66810155 is a wasteful number, since it uses less digits than its factorization.

66810155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13362036.

The product of its (nonzero) digits is 7200, while the sum is 32.

The square root of 66810155 is about 8173.7479163478. The cubic root of 66810155 is about 405.7708329201.

The spelling of 66810155 in words is "sixty-six million, eight hundred ten thousand, one hundred fifty-five".