247172561 has 2 divisors, whose sum is σ = 247172562. Its totient is φ = 247172560.

The previous prime is 247172521. The next prime is 247172573. The reversal of 247172561 is 165271742.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 206468161 + 40704400 = 14369^2 + 6380^2 .

It is a cyclic number.

It is not a de Polignac number, because 247172561 - 2²² = 242978257 is a prime.

It is a super-2 number, since 2×247172561² = 122188549822597442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (247172521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 123586280 + 123586281.

It is an arithmetic number, because the mean of its divisors is an integer number (123586281).

Almost surely, 2^247172561 is an apocalyptic number.

It is an amenable number.

247172561 is a deficient number, since it is larger than the sum of its proper divisors (1).

247172561 is an equidigital number, since it uses as much as digits as its factorization.

247172561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23520, while the sum is 35.

The square root of 247172561 is about 15721.7225837374. The cubic root of 247172561 is about 627.5766151433.

The spelling of 247172561 in words is "two hundred forty-seven million, one hundred seventy-two thousand, five hundred sixty-one".