247890721 has 12 divisors (see below), whose sum is σ = 271458540. Its totient is φ = 226237440.

The previous prime is 247890707. The next prime is 247890733. The reversal of 247890721 is 127098742.

It can be written as a sum of positive squares in 6 ways, for example, as 80550625 + 167340096 = 8975^2 + 12936^2 .

It is not a de Polignac number, because 247890721 - 2⁵ = 247890689 is a prime.

It is a super-2 number, since 2×247890721² = 122899619115799682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (247890751) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6801 + ... + 23281.

It is an arithmetic number, because the mean of its divisors is an integer number (22621545).

Almost surely, 2^247890721 is an apocalyptic number.

It is an amenable number.

247890721 is a deficient number, since it is larger than the sum of its proper divisors (23567819).

247890721 is a wasteful number, since it uses less digits than its factorization.

247890721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16596 (or 16583 counting only the distinct ones).

The product of its (nonzero) digits is 56448, while the sum is 40.

The square root of 247890721 is about 15744.5457540064. The cubic root of 247890721 is about 628.1838354861.

The spelling of 247890721 in words is "two hundred forty-seven million, eight hundred ninety thousand, seven hundred twenty-one".