6540216621 has 4 divisors (see below), whose sum is σ = 8720288832. Its totient is φ = 4360144412.

The previous prime is 6540216601. The next prime is 6540216691. The reversal of 6540216621 is 1266120456.

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.

It is a cyclic number.

It is not a de Polignac number, because 6540216621 - 2¹⁰ = 6540215597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6540216601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1090036101 + ... + 1090036106.

It is an arithmetic number, because the mean of its divisors is an integer number (2180072208).

Almost surely, 2^6540216621 is an apocalyptic number.

It is an amenable number.

6540216621 is a deficient number, since it is larger than the sum of its proper divisors (2180072211).

6540216621 is a wasteful number, since it uses less digits than its factorization.

6540216621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2180072210.

The product of its (nonzero) digits is 17280, while the sum is 33.

The square root of 6540216621 is about 80871.6057773060. The cubic root of 6540216621 is about 1870.0966159200.

The spelling of 6540216621 in words is "six billion, five hundred forty million, two hundred sixteen thousand, six hundred twenty-one".