684135821 has 8 divisors (see below), whose sum is σ = 689233920. Its totient is φ = 679047408.

The previous prime is 684135773. The next prime is 684135871. The reversal of 684135821 is 128531486.

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 684135821 - 2²² = 679941517 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 (684135871) 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, 199100 + ... + 202506.

It is an arithmetic number, because the mean of its divisors is an integer number (86154240).

Almost surely, 2^684135821 is an apocalyptic number.

It is an amenable number.

684135821 is a deficient number, since it is larger than the sum of its proper divisors (5098099).

684135821 is a wasteful number, since it uses less digits than its factorization.

684135821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4843.

The product of its digits is 46080, while the sum is 38.

The square root of 684135821 is about 26155.9901552207. The cubic root of 684135821 is about 881.1451263896.

The spelling of 684135821 in words is "six hundred eighty-four million, one hundred thirty-five thousand, eight hundred twenty-one".