660937681 has 2 divisors, whose sum is σ = 660937682. Its totient is φ = 660937680.

The previous prime is 660937661. The next prime is 660937687. The reversal of 660937681 is 186739066.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 568393281 + 92544400 = 23841^2 + 9620^2 .

It is a cyclic number.

It is not a de Polignac number, because 660937681 - 2²¹ = 658840529 is a prime.

It is a super-2 number, since 2×660937681² = 873677236331315522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (660937687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330468840 + 330468841.

It is an arithmetic number, because the mean of its divisors is an integer number (330468841).

Almost surely, 2^660937681 is an apocalyptic number.

It is an amenable number.

660937681 is a deficient number, since it is larger than the sum of its proper divisors (1).

660937681 is an equidigital number, since it uses as much as digits as its factorization.

660937681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 326592, while the sum is 46.

The square root of 660937681 is about 25708.7082717121. The cubic root of 660937681 is about 871.0708973307.

The spelling of 660937681 in words is "six hundred sixty million, nine hundred thirty-seven thousand, six hundred eighty-one".