6418819864521 has 9 divisors (see below), whose sum is σ = 9271639671879. Its totient is φ = 4279208175936.

The previous prime is 6418819864507. The next prime is 6418819864537. The reversal of 6418819864521 is 1254689188146.

It is a happy number.

The square root of 6418819864521 is 2533539.

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

6418819864521 is a `hidden beast` number, since 6 + 4 + 18 + 8 + 1 + 98 + 6 + 4 + 521 = 666.

It can be written as a sum of positive squares in only one way, i.e., 6036480455625 + 382339408896 = 2456925^2 + 618336^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 6418819864521 - 2⁴¹ = 4219796608969 is a prime.

It is not an unprimeable number, because it can be changed into a prime (6418819864591) 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, 7178361 + ... + 8022873.

Almost surely, 2^{6418819864521} is an apocalyptic number.

6418819864521 is the 2533539-th square number.

6418819864521 is the 1266770-th centered octagonal number.

It is an amenable number.

6418819864521 is a deficient number, since it is larger than the sum of its proper divisors (2852819807358).

6418819864521 is an frugal number, since it uses more digits than its factorization.

6418819864521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1689032 (or 844516 counting only the distinct ones).

The product of its digits is 26542080, while the sum is 63.

The spelling of 6418819864521 in words is "six trillion, four hundred eighteen billion, eight hundred nineteen million, eight hundred sixty-four thousand, five hundred twenty-one".