247855921 has 2 divisors, whose sum is σ = 247855922. Its totient is φ = 247855920.

The previous prime is 247855901. The next prime is 247856033. The reversal of 247855921 is 129558742.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 172791025 + 75064896 = 13145^2 + 8664^2 .

It is a cyclic number.

It is not a de Polignac number, because 247855921 - 2⁹ = 247855409 is a prime.

It is a super-2 number, since 2×247855921² = 122865115149516482, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (247855901) 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, 123927960 + 123927961.

It is an arithmetic number, because the mean of its divisors is an integer number (123927961).

Almost surely, 2^247855921 is an apocalyptic number.

It is an amenable number.

247855921 is a deficient number, since it is larger than the sum of its proper divisors (1).

247855921 is an equidigital number, since it uses as much as digits as its factorization.

247855921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 201600, while the sum is 43.

The square root of 247855921 is about 15743.4405705996. The cubic root of 247855921 is about 628.1544383652.

The spelling of 247855921 in words is "two hundred forty-seven million, eight hundred fifty-five thousand, nine hundred twenty-one".