6621981 has 8 divisors (see below), whose sum is σ = 8842080. Its totient is φ = 4408272.

The previous prime is 6621961. The next prime is 6621991. The reversal of 6621981 is 1891266.

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

It is not a de Polignac number, because 6621981 - 2⁵ = 6621949 is a prime.

It is a super-2 number, since 2×6621981² = 87701264728722, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6621911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1950 + ... + 4128.

It is an arithmetic number, because the mean of its divisors is an integer number (1105260).

Almost surely, 2^6621981 is an apocalyptic number.

It is an amenable number.

6621981 is a deficient number, since it is larger than the sum of its proper divisors (2220099).

6621981 is a wasteful number, since it uses less digits than its factorization.

6621981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3195.

The product of its digits is 5184, while the sum is 33.

The square root of 6621981 is about 2573.3210060154. The cubic root of 6621981 is about 187.7857545043.

The spelling of 6621981 in words is "six million, six hundred twenty-one thousand, nine hundred eighty-one".