247645 has 4 divisors (see below), whose sum is σ = 297180. Its totient is φ = 198112.

The previous prime is 247633. The next prime is 247649. The reversal of 247645 is 546742.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 42436 + 205209 = 206^2 + 453^2 .

It is a cyclic number.

It is not a de Polignac number, because 247645 - 2⁵ = 247613 is a prime.

It is a super-2 number, since 2×247645² = 122656092050, which contains 22 as substring.

247645 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (247649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24760 + ... + 24769.

It is an arithmetic number, because the mean of its divisors is an integer number (74295).

2²⁴⁷⁶⁴⁵ is an apocalyptic number.

It is an amenable number.

247645 is a deficient number, since it is larger than the sum of its proper divisors (49535).

247645 is an equidigital number, since it uses as much as digits as its factorization.

247645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49534.

The product of its digits is 6720, while the sum is 28.

The square root of 247645 is about 497.6394276984. The cubic root of 247645 is about 62.7976205030.

The spelling of 247645 in words is "two hundred forty-seven thousand, six hundred forty-five".