660405331 has 2 divisors, whose sum is σ = 660405332. Its totient is φ = 660405330.

The previous prime is 660405329. The next prime is 660405397. The reversal of 660405331 is 133504066.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 660405331 - 2¹ = 660405329 is a prime.

It is a super-2 number, since 2×660405331² = 872270402426439122, which contains 22 as substring.

Together with 660405329, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 660405331.

It is not a weakly prime, because it can be changed into another prime (660405631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330202665 + 330202666.

It is an arithmetic number, because the mean of its divisors is an integer number (330202666).

Almost surely, 2^660405331 is an apocalyptic number.

660405331 is a deficient number, since it is larger than the sum of its proper divisors (1).

660405331 is an equidigital number, since it uses as much as digits as its factorization.

660405331 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6480, while the sum is 28.

The square root of 660405331 is about 25698.3526903963. The cubic root of 660405331 is about 870.8369674861.

Adding to 660405331 its reverse (133504066), we get a palindrome (793909397).

The spelling of 660405331 in words is "six hundred sixty million, four hundred five thousand, three hundred thirty-one".