6691521 has 8 divisors (see below), whose sum is σ = 9001440. Its totient is φ = 4421312.

The previous prime is 6691519. The next prime is 6691541. The reversal of 6691521 is 1251966.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6691521 - 2¹ = 6691519 is a prime.

It is an Ulam number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6691501) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9531 + ... + 10208.

It is an arithmetic number, because the mean of its divisors is an integer number (1125180).

Almost surely, 2^6691521 is an apocalyptic number.

It is an amenable number.

6691521 is a deficient number, since it is larger than the sum of its proper divisors (2309919).

6691521 is a wasteful number, since it uses less digits than its factorization.

6691521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19855.

The product of its digits is 3240, while the sum is 30.

The square root of 6691521 is about 2586.7974408523. The cubic root of 6691521 is about 188.4408039513.

The spelling of 6691521 in words is "six million, six hundred ninety-one thousand, five hundred twenty-one".