66991003 has 4 divisors (see below), whose sum is σ = 67028040. Its totient is φ = 66953968.

The previous prime is 66990997. The next prime is 66991021. The reversal of 66991003 is 30019966.

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 66991003 - 2⁹ = 66990491 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66991003.

It is not an unprimeable number, because it can be changed into a prime (66994003) 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, 15658 + ... + 19471.

It is an arithmetic number, because the mean of its divisors is an integer number (16757010).

Almost surely, 2^66991003 is an apocalyptic number.

66991003 is a deficient number, since it is larger than the sum of its proper divisors (37037).

66991003 is a wasteful number, since it uses less digits than its factorization.

66991003 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37036.

The product of its (nonzero) digits is 8748, while the sum is 34.

The square root of 66991003 is about 8184.8031741759. The cubic root of 66991003 is about 406.1366292565.

The spelling of 66991003 in words is "sixty-six million, nine hundred ninety-one thousand, three".