6651581 has 8 divisors (see below), whose sum is σ = 6867840. Its totient is φ = 6438528.

The previous prime is 6651571. The next prime is 6651583. The reversal of 6651581 is 1851566.

It is a happy number.

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 6651581 - 2⁶ = 6651517 is a prime.

It is a super-2 number, since 2×6651581² = 88487059599122, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6651583) 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, 3830 + ... + 5288.

It is an arithmetic number, because the mean of its divisors is an integer number (858480).

Almost surely, 2^6651581 is an apocalyptic number.

It is an amenable number.

6651581 is a deficient number, since it is larger than the sum of its proper divisors (216259).

6651581 is a wasteful number, since it uses less digits than its factorization.

6651581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1603.

The product of its digits is 7200, while the sum is 32.

The square root of 6651581 is about 2579.0659161797. The cubic root of 6651581 is about 188.0651370036.

The spelling of 6651581 in words is "six million, six hundred fifty-one thousand, five hundred eighty-one".