66491597 has 6 divisors (see below), whose sum is σ = 69508782. Its totient is φ = 63600152.

The previous prime is 66491591. The next prime is 66491599. The reversal of 66491597 is 79519466.

It can be written as a sum of positive squares in only one way, i.e., 60435076 + 6056521 = 7774^2 + 2461^2 .

It is not a de Polignac number, because 66491597 - 2¹⁰ = 66490573 is a prime.

It is a super-2 number, since 2×66491597² = 8842264943220818, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66491591) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 62318 + ... + 63375.

It is an arithmetic number, because the mean of its divisors is an integer number (11584797).

Almost surely, 2^66491597 is an apocalyptic number.

It is an amenable number.

66491597 is a deficient number, since it is larger than the sum of its proper divisors (3017185).

66491597 is a wasteful number, since it uses less digits than its factorization.

66491597 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125739 (or 125716 counting only the distinct ones).

The product of its digits is 408240, while the sum is 47.

The square root of 66491597 is about 8154.2379778861. The cubic root of 66491597 is about 405.1248855326.

The spelling of 66491597 in words is "sixty-six million, four hundred ninety-one thousand, five hundred ninety-seven".