247288721 has 2 divisors, whose sum is σ = 247288722. Its totient is φ = 247288720.

The previous prime is 247288697. The next prime is 247288787. The reversal of 247288721 is 127882742.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 229098496 + 18190225 = 15136^2 + 4265^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-247288721 is a prime.

It is a super-2 number, since 2×247288721² = 122303423067631682, which contains 22 as substring.

It is equal to p_13538939 and since 247288721 and 13538939 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (247288121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 123644360 + 123644361.

It is an arithmetic number, because the mean of its divisors is an integer number (123644361).

Almost surely, 2^247288721 is an apocalyptic number.

It is an amenable number.

247288721 is a deficient number, since it is larger than the sum of its proper divisors (1).

247288721 is an equidigital number, since it uses as much as digits as its factorization.

247288721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 100352, while the sum is 41.

The square root of 247288721 is about 15725.4164014820. The cubic root of 247288721 is about 627.6749106856.

The spelling of 247288721 in words is "two hundred forty-seven million, two hundred eighty-eight thousand, seven hundred twenty-one".