6541439818021 has 2 divisors, whose sum is σ = 6541439818022. Its totient is φ = 6541439818020.

The previous prime is 6541439818013. The next prime is 6541439818031. The reversal of 6541439818021 is 1208189341456.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6142317856900 + 399121961121 = 2478370^2 + 631761^2 .

It is a cyclic number.

It is not a de Polignac number, because 6541439818021 - 2³ = 6541439818013 is a prime.

It is a super-2 number, since 2×6541439818021² (a number of 26 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 6541439818021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6541439818031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3270719909010 + 3270719909011.

It is an arithmetic number, because the mean of its divisors is an integer number (3270719909011).

Almost surely, 2^{6541439818021} is an apocalyptic number.

It is an amenable number.

6541439818021 is a deficient number, since it is larger than the sum of its proper divisors (1).

6541439818021 is an equidigital number, since it uses as much as digits as its factorization.

6541439818021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1658880, while the sum is 52.

The spelling of 6541439818021 in words is "six trillion, five hundred forty-one billion, four hundred thirty-nine million, eight hundred eighteen thousand, twenty-one".