8125039981 has 2 divisors, whose sum is σ = 8125039982. Its totient is φ = 8125039980.

The previous prime is 8125039969. The next prime is 8125039991. The reversal of 8125039981 is 1899305218.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7962885225 + 162154756 = 89235^2 + 12734^2 .

It is a cyclic number.

It is not a de Polignac number, because 8125039981 - 2⁹ = 8125039469 is a prime.

It is a super-2 number, since 2×8125039981² (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 (8125039921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4062519990 + 4062519991.

It is an arithmetic number, because the mean of its divisors is an integer number (4062519991).

Almost surely, 2^8125039981 is an apocalyptic number.

It is an amenable number.

8125039981 is a deficient number, since it is larger than the sum of its proper divisors (1).

8125039981 is an equidigital number, since it uses as much as digits as its factorization.

8125039981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 155520, while the sum is 46.

The square root of 8125039981 is about 90139.0036610124. The cubic root of 8125039981 is about 2010.3661767791.

The spelling of 8125039981 in words is "eight billion, one hundred twenty-five million, thirty-nine thousand, nine hundred eighty-one".