1315634821 has 4 divisors (see below), whose sum is σ = 1316483532. Its totient is φ = 1314786112.

The previous prime is 1315634813. The next prime is 1315634867. The reversal of 1315634821 is 1284365131.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1284365131 = 7 ⋅183480733.

It can be written as a sum of positive squares in 2 ways, for example, as 335256100 + 980378721 = 18310^2 + 31311^2 .

It is a cyclic number.

It is not a de Polignac number, because 1315634821 - 2³ = 1315634813 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1315634521) 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, 422026 + ... + 425131.

It is an arithmetic number, because the mean of its divisors is an integer number (329120883).

Almost surely, 2^1315634821 is an apocalyptic number.

It is an amenable number.

1315634821 is a deficient number, since it is larger than the sum of its proper divisors (848711).

1315634821 is an equidigital number, since it uses as much as digits as its factorization.

1315634821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 848710.

The product of its digits is 17280, while the sum is 34.

The square root of 1315634821 is about 36271.6807027190. The cubic root of 1315634821 is about 1095.7507749890.

Adding to 1315634821 its reverse (1284365131), we get a palindrome (2599999952).

The spelling of 1315634821 in words is "one billion, three hundred fifteen million, six hundred thirty-four thousand, eight hundred twenty-one".