7999981 has 4 divisors (see below), whose sum is σ = 8727264. Its totient is φ = 7272700.

The previous prime is 7999963. The next prime is 7999993. The reversal of 7999981 is 1899997.

7999981 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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 7999981 - 2¹¹ = 7997933 is a prime.

It is a super-2 number, since 2×7999981² = 127999392000722, 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 (7999921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 363625 + ... + 363646.

It is an arithmetic number, because the mean of its divisors is an integer number (2181816).

Almost surely, 2^7999981 is an apocalyptic number.

It is an amenable number.

7999981 is a deficient number, since it is larger than the sum of its proper divisors (727283).

7999981 is a wasteful number, since it uses less digits than its factorization.

7999981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 727282.

The product of its digits is 367416, while the sum is 52.

The square root of 7999981 is about 2828.4237659870. The cubic root of 7999981 is about 199.9998416665. Note that the first 3 decimals are identical.

The spelling of 7999981 in words is "seven million, nine hundred ninety-nine thousand, nine hundred eighty-one".