685666213621 has 8 divisors (see below), whose sum is σ = 701218103040. Its totient is φ = 670154459568.

The previous prime is 685666213597. The next prime is 685666213627. The reversal of 685666213621 is 126312666586.

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 685666213621 - 2¹⁵ = 685666180853 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (685666213627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9999286 + ... + 10067623.

It is an arithmetic number, because the mean of its divisors is an integer number (87652262880).

Almost surely, 2^685666213621 is an apocalyptic number.

It is an amenable number.

685666213621 is a deficient number, since it is larger than the sum of its proper divisors (15551889419).

685666213621 is a wasteful number, since it uses less digits than its factorization.

685666213621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20067683.

The product of its digits is 3732480, while the sum is 52.

The spelling of 685666213621 in words is "six hundred eighty-five billion, six hundred sixty-six million, two hundred thirteen thousand, six hundred twenty-one".