6645891 has 8 divisors (see below), whose sum is σ = 10127104. Its totient is φ = 3797640.

The previous prime is 6645887. The next prime is 6645907. The reversal of 6645891 is 1985466.

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

It is not a de Polignac number, because 6645891 - 2² = 6645887 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6645851) 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, 158215 + ... + 158256.

It is an arithmetic number, because the mean of its divisors is an integer number (1265888).

Almost surely, 2^6645891 is an apocalyptic number.

6645891 is a deficient number, since it is larger than the sum of its proper divisors (3481213).

6645891 is a wasteful number, since it uses less digits than its factorization.

6645891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 316481.

The product of its digits is 51840, while the sum is 39.

The square root of 6645891 is about 2577.9625676103. The cubic root of 6645891 is about 188.0114958264.

It can be divided in two parts, 664 and 5891, that added together give a triangular number (6555 = T₁₁₄).

The spelling of 6645891 in words is "six million, six hundred forty-five thousand, eight hundred ninety-one".