6639388043401 has 27 divisors (see below), whose sum is σ = 6888419459103. Its totient is φ = 6399288467520.

The previous prime is 6639388043347. The next prime is 6639388043459. The reversal of 6639388043401 is 1043408839366.

The square root of 6639388043401 is 2576701.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 13 ways, for example, as 5656077819001 + 983310224400 = 2378251^2 + 991620^2 .

It is not a de Polignac number, because 6639388043401 - 2¹¹ = 6639388041353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6639388043461) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 8330473935 + ... + 8330474731.

Almost surely, 2^{6639388043401} is an apocalyptic number.

6639388043401 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

6639388043401 is the 2576701-st square number.

6639388043401 is the 1288351-st centered octagonal number.

It is an amenable number.

6639388043401 is a deficient number, since it is larger than the sum of its proper divisors (249031415702).

6639388043401 is an frugal number, since it uses more digits than its factorization.

6639388043401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1822 (or 911 counting only the distinct ones).

The product of its (nonzero) digits is 8957952, while the sum is 55.

The spelling of 6639388043401 in words is "six trillion, six hundred thirty-nine billion, three hundred eighty-eight million, forty-three thousand, four hundred one".