660405389 has 6 divisors (see below), whose sum is σ = 768226734. Its totient is φ = 566061720.

The previous prime is 660405331. The next prime is 660405397. The reversal of 660405389 is 983504066.

It can be written as a sum of positive squares in only one way, i.e., 636805225 + 23600164 = 25235^2 + 4858^2 .

It is not a de Polignac number, because 660405389 - 2¹⁶ = 660339853 is a prime.

It is a super-2 number, since 2×660405389² = 872270555640482642, 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 (660405329) 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, 6738782 + ... + 6738879.

It is an arithmetic number, because the mean of its divisors is an integer number (128037789).

Almost surely, 2^660405389 is an apocalyptic number.

It is an amenable number.

660405389 is a deficient number, since it is larger than the sum of its proper divisors (107821345).

660405389 is a wasteful number, since it uses less digits than its factorization.

660405389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13477675 (or 13477668 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 41.

The square root of 660405389 is about 25698.3538188733. The cubic root of 660405389 is about 870.8369929798.

The spelling of 660405389 in words is "six hundred sixty million, four hundred five thousand, three hundred eighty-nine".