6511921 has 16 divisors (see below), whose sum is σ = 7580160. Its totient is φ = 5544000.

The previous prime is 6511909. The next prime is 6511937. The reversal of 6511921 is 1291156.

It is a cyclic number.

It is not a de Polignac number, because 6511921 - 2¹¹ = 6509873 is a prime.

It is a super-2 number, since 2×6511921² = 84810230220482, which contains 22 as substring.

It is a Duffinian number.

6511921 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (6511961) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8296 + ... + 9046.

It is an arithmetic number, because the mean of its divisors is an integer number (473760).

Almost surely, 2^6511921 is an apocalyptic number.

It is an amenable number.

6511921 is a deficient number, since it is larger than the sum of its proper divisors (1068239).

6511921 is a wasteful number, since it uses less digits than its factorization.

6511921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816.

The product of its digits is 540, while the sum is 25.

The square root of 6511921 is about 2551.8465862979. The cubic root of 6511921 is about 186.7395785889.

It can be divided in two parts, 651 and 1921, that multiplied together give a triangular number (1250571 = T₁₅₈₁).

The spelling of 6511921 in words is "six million, five hundred eleven thousand, nine hundred twenty-one".