6521151665 has 16 divisors (see below), whose sum is σ = 8947581312. Its totient is φ = 4469503104.

The previous prime is 6521151653. The next prime is 6521151673. The reversal of 6521151665 is 5661511256.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 6521151665 - 2¹⁰ = 6521150641 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31202 + ... + 118388.

It is an arithmetic number, because the mean of its divisors is an integer number (559223832).

Almost surely, 2^6521151665 is an apocalyptic number.

It is an amenable number.

6521151665 is a deficient number, since it is larger than the sum of its proper divisors (2426429647).

6521151665 is a wasteful number, since it uses less digits than its factorization.

6521151665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89336.

The product of its digits is 54000, while the sum is 38.

The square root of 6521151665 is about 80753.6479980936. The cubic root of 6521151665 is about 1868.2777154401.

The spelling of 6521151665 in words is "six billion, five hundred twenty-one million, one hundred fifty-one thousand, six hundred sixty-five".