6521681 has 4 divisors (see below), whose sum is σ = 6673392. Its totient is φ = 6369972.

The previous prime is 6521677. The next prime is 6521689. The reversal of 6521681 is 1861256.

It is a happy number.

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 6521681 - 2² = 6521677 is a prime.

It is a super-2 number, since 2×6521681² = 85064646131522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6521689) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 75791 + ... + 75876.

It is an arithmetic number, because the mean of its divisors is an integer number (1668348).

Almost surely, 2^6521681 is an apocalyptic number.

It is an amenable number.

6521681 is a deficient number, since it is larger than the sum of its proper divisors (151711).

6521681 is a wasteful number, since it uses less digits than its factorization.

6521681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151710.

The product of its digits is 2880, while the sum is 29.

The square root of 6521681 is about 2553.7582109511. The cubic root of 6521681 is about 186.8328264693.

The spelling of 6521681 in words is "six million, five hundred twenty-one thousand, six hundred eighty-one".