66643819 has 8 divisors (see below), whose sum is σ = 74476080. Its totient is φ = 59107200.

The previous prime is 66643813. The next prime is 66643883. The reversal of 66643819 is 91834666.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66643819 is a prime.

It is a super-2 number, since 2×66643819² = 8882797221809522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66643813) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 73434 + ... + 74335.

It is an arithmetic number, because the mean of its divisors is an integer number (9309510).

Almost surely, 2^66643819 is an apocalyptic number.

66643819 is a deficient number, since it is larger than the sum of its proper divisors (7832261).

66643819 is a wasteful number, since it uses less digits than its factorization.

66643819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147821.

The product of its digits is 186624, while the sum is 43.

The square root of 66643819 is about 8163.5665612525. The cubic root of 66643819 is about 405.4338063709.

The spelling of 66643819 in words is "sixty-six million, six hundred forty-three thousand, eight hundred nineteen".