66557913 has 4 divisors (see below), whose sum is σ = 88743888. Its totient is φ = 44371940.

The previous prime is 66557903. The next prime is 66557917. The reversal of 66557913 is 31975566.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66557913 - 2⁸ = 66557657 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66557917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11092983 + ... + 11092988.

It is an arithmetic number, because the mean of its divisors is an integer number (22185972).

Almost surely, 2^66557913 is an apocalyptic number.

It is an amenable number.

66557913 is a deficient number, since it is larger than the sum of its proper divisors (22185975).

66557913 is a wasteful number, since it uses less digits than its factorization.

66557913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22185974.

The product of its digits is 170100, while the sum is 42.

The square root of 66557913 is about 8158.3033162539. The cubic root of 66557913 is about 405.2595257793.

The spelling of 66557913 in words is "sixty-six million, five hundred fifty-seven thousand, nine hundred thirteen".