6615618198021 has 96 divisors (see below), whose sum is σ = 12225432360960. Its totient is φ = 3491300159424.

The previous prime is 6615618198019. The next prime is 6615618198023. The reversal of 6615618198021 is 1208918165166.

6615618198021 is a `hidden beast` number, since 6 + 6 + 1 + 5 + 618 + 19 + 8 + 0 + 2 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (6615618198019) and next prime (6615618198023).

It is not a de Polignac number, because 6615618198021 - 2¹ = 6615618198019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6615618198023) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1780915 + ... + 4050048.

It is an arithmetic number, because the mean of its divisors is an integer number (127348253760).

Almost surely, 2^{6615618198021} is an apocalyptic number.

It is an amenable number.

6615618198021 is a deficient number, since it is larger than the sum of its proper divisors (5609814162939).

6615618198021 is a wasteful number, since it uses less digits than its factorization.

6615618198021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5831037 (or 5831025 counting only the distinct ones).

The product of its (nonzero) digits is 1244160, while the sum is 54.

The spelling of 6615618198021 in words is "six trillion, six hundred fifteen billion, six hundred eighteen million, one hundred ninety-eight thousand, twenty-one".