665497581 has 16 divisors (see below), whose sum is σ = 1035669504. Its totient is φ = 372192624.

The previous prime is 665497579. The next prime is 665497583. The reversal of 665497581 is 185794566.

It is an interprime number because it is at equal distance from previous prime (665497579) and next prime (665497583).

It is not a de Polignac number, because 665497581 - 2¹ = 665497579 is a prime.

It is a super-2 number, since 2×665497581² = 885774060633703122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665497583) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 336145 + ... + 338118.

It is an arithmetic number, because the mean of its divisors is an integer number (64729344).

Almost surely, 2^665497581 is an apocalyptic number.

It is an amenable number.

665497581 is a deficient number, since it is larger than the sum of its proper divisors (370171923).

665497581 is a wasteful number, since it uses less digits than its factorization.

665497581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 674320.

The product of its digits is 1814400, while the sum is 51.

The square root of 665497581 is about 25797.2397942105. The cubic root of 665497581 is about 873.0695207512.

The spelling of 665497581 in words is "six hundred sixty-five million, four hundred ninety-seven thousand, five hundred eighty-one".