6681981 has 4 divisors (see below), whose sum is σ = 8909312. Its totient is φ = 4454652.

The previous prime is 6681979. The next prime is 6681989. The reversal of 6681981 is 1891866.

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 not a de Polignac number, because 6681981 - 2¹ = 6681979 is a prime.

It is a super-2 number, since 2×6681981² = 89297740168722, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6681989) 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, 1113661 + ... + 1113666.

It is an arithmetic number, because the mean of its divisors is an integer number (2227328).

Almost surely, 2^6681981 is an apocalyptic number.

It is an amenable number.

6681981 is a deficient number, since it is larger than the sum of its proper divisors (2227331).

6681981 is a wasteful number, since it uses less digits than its factorization.

6681981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2227330.

The product of its digits is 20736, while the sum is 39.

The square root of 6681981 is about 2584.9528042113. The cubic root of 6681981 is about 188.3512089610.

The spelling of 6681981 in words is "six million, six hundred eighty-one thousand, nine hundred eighty-one".