6421718041538 has 18 divisors (see below), whose sum is σ = 9750482103609. Its totient is φ = 3172027037592.

The previous prime is 6421718041537. The next prime is 6421718041549. The reversal of 6421718041538 is 8351408171246.

It can be written as a sum of positive squares in 2 ways, for example, as 6417320097049 + 4397944489 = 2533243^2 + 66317^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=1791887.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6421718041537) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 297442448 + ... + 297464036.

Almost surely, 2^{6421718041538} is an apocalyptic number.

6421718041538 is a deficient number, since it is larger than the sum of its proper divisors (3328764062071).

6421718041538 is an frugal number, since it uses more digits than its factorization.

6421718041538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43346 (or 21674 counting only the distinct ones).

The product of its (nonzero) digits is 1290240, while the sum is 50.

Multiplying 6421718041538 by its sum of digits (50), we get a square (321085902076900 = 17918870²).

The spelling of 6421718041538 in words is "six trillion, four hundred twenty-one billion, seven hundred eighteen million, forty-one thousand, five hundred thirty-eight".