6542661521 has 4 divisors (see below), whose sum is σ = 7137448944. Its totient is φ = 5947874100.

The previous prime is 6542661509. The next prime is 6542661529. The reversal of 6542661521 is 1251662456.

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 a de Polignac number, because none of the positive numbers 2^k-6542661521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6542661529) 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, 297393695 + ... + 297393716.

It is an arithmetic number, because the mean of its divisors is an integer number (1784362236).

Almost surely, 2^6542661521 is an apocalyptic number.

It is an amenable number.

6542661521 is a deficient number, since it is larger than the sum of its proper divisors (594787423).

6542661521 is a wasteful number, since it uses less digits than its factorization.

6542661521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 594787422.

The product of its digits is 86400, while the sum is 38.

The square root of 6542661521 is about 80886.7203006773. The cubic root of 6542661521 is about 1870.3296168466.

The spelling of 6542661521 in words is "six billion, five hundred forty-two million, six hundred sixty-one thousand, five hundred twenty-one".