642686691 has 8 divisors (see below), whose sum is σ = 857129040. Its totient is φ = 428351072.

The previous prime is 642686687. The next prime is 642686743. The reversal of 642686691 is 196686246.

It is a happy number.

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 642686691 - 2² = 642686687 is a prime.

It is a super-3 number, since 3×642686691³ (a number of 27 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 642686691.

It is not an unprimeable number, because it can be changed into a prime (642686651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11376 + ... + 37613.

It is an arithmetic number, because the mean of its divisors is an integer number (107141130).

Almost surely, 2^642686691 is an apocalyptic number.

642686691 is a deficient number, since it is larger than the sum of its proper divisors (214442349).

642686691 is a wasteful number, since it uses less digits than its factorization.

642686691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53365.

The product of its digits is 746496, while the sum is 48.

The square root of 642686691 is about 25351.2660630589. The cubic root of 642686691 is about 862.9780883992.

The spelling of 642686691 in words is "six hundred forty-two million, six hundred eighty-six thousand, six hundred ninety-one".