247428721 has 2 divisors, whose sum is σ = 247428722. Its totient is φ = 247428720.

The previous prime is 247428719. The next prime is 247428737. The reversal of 247428721 is 127824742.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 206928225 + 40500496 = 14385^2 + 6364^2 .

It is a cyclic number.

It is not a de Polignac number, because 247428721 - 2¹ = 247428719 is a prime.

It is a super-2 number, since 2×247428721² = 122441943951391682, which contains 22 as substring.

Together with 247428719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (247428781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 123714360 + 123714361.

It is an arithmetic number, because the mean of its divisors is an integer number (123714361).

Almost surely, 2^247428721 is an apocalyptic number.

It is an amenable number.

247428721 is a deficient number, since it is larger than the sum of its proper divisors (1).

247428721 is an equidigital number, since it uses as much as digits as its factorization.

247428721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 50176, while the sum is 37.

The square root of 247428721 is about 15729.8671640926. The cubic root of 247428721 is about 627.7933389332.

The spelling of 247428721 in words is "two hundred forty-seven million, four hundred twenty-eight thousand, seven hundred twenty-one".