247521 has 4 divisors (see below), whose sum is σ = 330032. Its totient is φ = 165012.

The previous prime is 247519. The next prime is 247529. The reversal of 247521 is 125742.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 247521 - 2¹ = 247519 is a prime.

It is a super-2 number, since 2×247521² = 122533290882, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is a nialpdrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (247529) 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, 41251 + ... + 41256.

It is an arithmetic number, because the mean of its divisors is an integer number (82508).

2²⁴⁷⁵²¹ is an apocalyptic number.

It is an amenable number.

247521 is a deficient number, since it is larger than the sum of its proper divisors (82511).

247521 is an equidigital number, since it uses as much as digits as its factorization.

247521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82510.

The product of its digits is 560, while the sum is 21.

The square root of 247521 is about 497.5148238998. The cubic root of 247521 is about 62.7871374796.

It can be divided in two parts, 24752 and 1, that added together give a triangular number (24753 = T₂₂₂).

The spelling of 247521 in words is "two hundred forty-seven thousand, five hundred twenty-one".