7681981 has 4 divisors (see below), whose sum is σ = 7690464. Its totient is φ = 7673500.

The previous prime is 7681969. The next prime is 7681991. The reversal of 7681981 is 1891867.

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, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1891867 = 107 ⋅17681.

It is a cyclic number.

It is not a de Polignac number, because 7681981 - 2¹⁷ = 7550909 is a prime.

It is a super-2 number, since 2×7681981² = 118025664168722, which contains 22 as substring.

It is a Duffinian number.

7681981 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7681991) 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, 2695 + ... + 4756.

It is an arithmetic number, because the mean of its divisors is an integer number (1922616).

Almost surely, 2^7681981 is an apocalyptic number.

It is an amenable number.

7681981 is a deficient number, since it is larger than the sum of its proper divisors (8483).

7681981 is a wasteful number, since it uses less digits than its factorization.

7681981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8482.

The product of its digits is 24192, while the sum is 40.

The square root of 7681981 is about 2771.6386849660. The cubic root of 7681981 is about 197.3139282593.

The spelling of 7681981 in words is "seven million, six hundred eighty-one thousand, nine hundred eighty-one".