66814391 has 6 divisors (see below), whose sum is σ = 77722920. Its totient is φ = 57269436.

The previous prime is 66814387. The next prime is 66814411. The reversal of 66814391 is 19341866.

It is not a de Polignac number, because 66814391 - 2² = 66814387 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 (66814691) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 681731 + ... + 681828.

It is an arithmetic number, because the mean of its divisors is an integer number (12953820).

Almost surely, 2^66814391 is an apocalyptic number.

66814391 is a deficient number, since it is larger than the sum of its proper divisors (10908529).

66814391 is a wasteful number, since it uses less digits than its factorization.

66814391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1363573 (or 1363566 counting only the distinct ones).

The product of its digits is 31104, while the sum is 38.

The square root of 66814391 is about 8174.0070344966. The cubic root of 66814391 is about 405.7794085073.

The spelling of 66814391 in words is "sixty-six million, eight hundred fourteen thousand, three hundred ninety-one".