6647981 has 4 divisors (see below), whose sum is σ = 6862464. Its totient is φ = 6433500.

The previous prime is 6647959. The next prime is 6647983. The reversal of 6647981 is 1897466.

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 6647981 - 2⁶ = 6647917 is a prime.

It is a super-2 number, since 2×6647981² = 88391302752722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6647983) 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, 107195 + ... + 107256.

It is an arithmetic number, because the mean of its divisors is an integer number (1715616).

Almost surely, 2^6647981 is an apocalyptic number.

It is an amenable number.

6647981 is a deficient number, since it is larger than the sum of its proper divisors (214483).

6647981 is a wasteful number, since it uses less digits than its factorization.

6647981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214482.

The product of its digits is 72576, while the sum is 41.

The square root of 6647981 is about 2578.3678946186. The cubic root of 6647981 is about 188.0312023810.

The spelling of 6647981 in words is "six million, six hundred forty-seven thousand, nine hundred eighty-one".