6538728021 has 16 divisors (see below), whose sum is σ = 10167120000. Its totient is φ = 3736415424.

The previous prime is 6538728013. The next prime is 6538728047. The reversal of 6538728021 is 1208278356.

It is not a de Polignac number, because 6538728021 - 2³ = 6538728013 is a prime.

It is a super-2 number, since 2×6538728021² = 85509928265221152882, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6538728821) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3176196 + ... + 3178253.

It is an arithmetic number, because the mean of its divisors is an integer number (635445000).

Almost surely, 2^6538728021 is an apocalyptic number.

It is an amenable number.

6538728021 is a deficient number, since it is larger than the sum of its proper divisors (3628391979).

6538728021 is an equidigital number, since it uses as much as digits as its factorization.

6538728021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6354473 (or 6354459 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 42.

The square root of 6538728021 is about 80862.4017761036. The cubic root of 6538728021 is about 1869.9547227067.

The spelling of 6538728021 in words is "six billion, five hundred thirty-eight million, seven hundred twenty-eight thousand, twenty-one".