6658999821 has 8 divisors (see below), whose sum is σ = 9865184960. Its totient is φ = 4439333196.

The previous prime is 6658999751. The next prime is 6658999849. The reversal of 6658999821 is 1289998566.

It is not a de Polignac number, because 6658999821 - 2⁹ = 6658999309 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 (6658999861) 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, 123314785 + ... + 123314838.

It is an arithmetic number, because the mean of its divisors is an integer number (1233148120).

Almost surely, 2^6658999821 is an apocalyptic number.

It is an amenable number.

6658999821 is a deficient number, since it is larger than the sum of its proper divisors (3206185139).

6658999821 is a wasteful number, since it uses less digits than its factorization.

6658999821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 246629632 (or 246629626 counting only the distinct ones).

The product of its digits is 16796160, while the sum is 63.

The square root of 6658999821 is about 81602.6949371159. The cubic root of 6658999821 is about 1881.3503032123.

The spelling of 6658999821 in words is "six billion, six hundred fifty-eight million, nine hundred ninety-nine thousand, eight hundred twenty-one".