315021521 has 4 divisors (see below), whose sum is σ = 315929712. Its totient is φ = 314113332.

The previous prime is 315021503. The next prime is 315021527. The reversal of 315021521 is 125120513.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 125120513 = 7 ⋅17874359.

It is a cyclic number.

It is not a de Polignac number, because 315021521 - 2¹⁴ = 315005137 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 315021493 and 315021502.

It is not an unprimeable number, because it can be changed into a prime (315021527) 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, 453575 + ... + 454268.

It is an arithmetic number, because the mean of its divisors is an integer number (78982428).

Almost surely, 2^315021521 is an apocalyptic number.

It is an amenable number.

315021521 is a deficient number, since it is larger than the sum of its proper divisors (908191).

315021521 is an equidigital number, since it uses as much as digits as its factorization.

315021521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 908190.

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 315021521 is about 17748.8456244343. The cubic root of 315021521 is about 680.4247065722.

The spelling of 315021521 in words is "three hundred fifteen million, twenty-one thousand, five hundred twenty-one".