247913921 has 6 divisors (see below), whose sum is σ = 254063922. Its totient is φ = 241768880.

The previous prime is 247913917. The next prime is 247913927. The reversal of 247913921 is 129319742.

It can be written as a sum of positive squares in only one way, i.e., 151167025 + 96746896 = 12295^2 + 9836^2 .

It is not a de Polignac number, because 247913921 - 2² = 247913917 is a prime.

It is a super-2 number, since 2×247913921² = 122922624451188482, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (247913927) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 99590 + ... + 102048.

It is an arithmetic number, because the mean of its divisors is an integer number (42343987).

Almost surely, 2^247913921 is an apocalyptic number.

It is an amenable number.

247913921 is a deficient number, since it is larger than the sum of its proper divisors (6150001).

247913921 is an frugal number, since it uses more digits than its factorization.

247913921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4959 (or 2500 counting only the distinct ones).

The product of its digits is 27216, while the sum is 38.

The square root of 247913921 is about 15745.2824998474. The cubic root of 247913921 is about 628.2034320383.

The spelling of 247913921 in words is "two hundred forty-seven million, nine hundred thirteen thousand, nine hundred twenty-one".