915725981 has 2 divisors, whose sum is σ = 915725982. Its totient is φ = 915725980.

The previous prime is 915725903. The next prime is 915725983. The reversal of 915725981 is 189527519.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 826045081 + 89680900 = 28741^2 + 9470^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-915725981 is a prime.

It is a super-2 number, since 2×915725981² = 1677108144556824722, which contains 22 as substring.

Together with 915725983, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (915725983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 457862990 + 457862991.

It is an arithmetic number, because the mean of its divisors is an integer number (457862991).

Almost surely, 2^915725981 is an apocalyptic number.

It is an amenable number.

915725981 is a deficient number, since it is larger than the sum of its proper divisors (1).

915725981 is an equidigital number, since it uses as much as digits as its factorization.

915725981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 226800, while the sum is 47.

The square root of 915725981 is about 30260.9646409363. The cubic root of 915725981 is about 971.0803780558.

The spelling of 915725981 in words is "nine hundred fifteen million, seven hundred twenty-five thousand, nine hundred eighty-one".