6639137060021 has 4 divisors (see below), whose sum is σ = 6639142484544. Its totient is φ = 6639131635500.

The previous prime is 6639137059987. The next prime is 6639137060047. The reversal of 6639137060021 is 1200607319366.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 6639137060021 - 2¹⁸ = 6639136797877 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 (6639137060921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 85796 + ... + 3644946.

It is an arithmetic number, because the mean of its divisors is an integer number (1659785621136).

Almost surely, 2^{6639137060021} is an apocalyptic number.

It is an amenable number.

6639137060021 is a deficient number, since it is larger than the sum of its proper divisors (5424523).

6639137060021 is a wasteful number, since it uses less digits than its factorization.

6639137060021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5424522.

The product of its (nonzero) digits is 244944, while the sum is 44.

The spelling of 6639137060021 in words is "six trillion, six hundred thirty-nine billion, one hundred thirty-seven million, sixty thousand, twenty-one".