7875971981 has 2 divisors, whose sum is σ = 7875971982. Its totient is φ = 7875971980.

The previous prime is 7875971969. The next prime is 7875972011. The reversal of 7875971981 is 1891795787.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7863255625 + 12716356 = 88675^2 + 3566^2 .

It is a cyclic number.

It is not a de Polignac number, because 7875971981 - 2²² = 7871777677 is a prime.

It is a super-2 number, since 2×7875971981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7875971921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3937985990 + 3937985991.

It is an arithmetic number, because the mean of its divisors is an integer number (3937985991).

Almost surely, 2^7875971981 is an apocalyptic number.

It is an amenable number.

7875971981 is a deficient number, since it is larger than the sum of its proper divisors (1).

7875971981 is an equidigital number, since it uses as much as digits as its factorization.

7875971981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8890560, while the sum is 62.

The square root of 7875971981 is about 88746.6730700368. The cubic root of 7875971981 is about 1989.6104538719.

The spelling of 7875971981 in words is "seven billion, eight hundred seventy-five million, nine hundred seventy-one thousand, nine hundred eighty-one".