669757681 has 8 divisors (see below), whose sum is σ = 672600104. Its totient is φ = 666921600.

The previous prime is 669757643. The next prime is 669757717. The reversal of 669757681 is 186757966.

It can be written as a sum of positive squares in 4 ways, for example, as 105267600 + 564490081 = 10260^2 + 23759^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 669757681 - 2⁹ = 669757169 is a prime.

It is a super-2 number, since 2×669757681² = 897150702516995522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (669757601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 370981 + ... + 372781.

It is an arithmetic number, because the mean of its divisors is an integer number (84075013).

Almost surely, 2^669757681 is an apocalyptic number.

It is an amenable number.

669757681 is a deficient number, since it is larger than the sum of its proper divisors (2842423).

669757681 is a wasteful number, since it uses less digits than its factorization.

669757681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3171.

The product of its digits is 3810240, while the sum is 55.

The square root of 669757681 is about 25879.6769879379. The cubic root of 669757681 is about 874.9285083358.

The spelling of 669757681 in words is "six hundred sixty-nine million, seven hundred fifty-seven thousand, six hundred eighty-one".