666787669 has 2 divisors, whose sum is σ = 666787670. Its totient is φ = 666787668.

The previous prime is 666787661. The next prime is 666787697. The reversal of 666787669 is 966787666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 524868100 + 141919569 = 22910^2 + 11913^2 .

It is a cyclic number.

It is not a de Polignac number, because 666787669 - 2³ = 666787661 is a prime.

It is a super-2 number, since 2×666787669² = 889211591060907122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666787661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333393834 + 333393835.

It is an arithmetic number, because the mean of its divisors is an integer number (333393835).

Almost surely, 2^666787669 is an apocalyptic number.

It is an amenable number.

666787669 is a deficient number, since it is larger than the sum of its proper divisors (1).

666787669 is an equidigital number, since it uses as much as digits as its factorization.

666787669 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27433728, while the sum is 61.

The square root of 666787669 is about 25822.2320685103. The cubic root of 666787669 is about 873.6333141763.

It can be divided in two parts, 66678 and 7669, that added together give a palindrome (74347).

The spelling of 666787669 in words is "six hundred sixty-six million, seven hundred eighty-seven thousand, six hundred sixty-nine".