6515901681 has 4 divisors (see below), whose sum is σ = 8687868912. Its totient is φ = 4343934452.

The previous prime is 6515901647. The next prime is 6515901701. The reversal of 6515901681 is 1861095156.

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 6515901681 - 2¹⁷ = 6515770609 is a prime.

It is a super-2 number, since 2×6515901681² = 84913949432917251522, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6515901611) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1085983611 + ... + 1085983616.

It is an arithmetic number, because the mean of its divisors is an integer number (2171967228).

Almost surely, 2^6515901681 is an apocalyptic number.

It is an amenable number.

6515901681 is a deficient number, since it is larger than the sum of its proper divisors (2171967231).

6515901681 is a wasteful number, since it uses less digits than its factorization.

6515901681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2171967230.

The product of its (nonzero) digits is 64800, while the sum is 42.

The square root of 6515901681 is about 80721.1352806686. The cubic root of 6515901681 is about 1867.7762160142.

The spelling of 6515901681 in words is "six billion, five hundred fifteen million, nine hundred one thousand, six hundred eighty-one".