21521120315 has 4 divisors (see below), whose sum is σ = 25825344384. Its totient is φ = 17216896248.

The previous prime is 21521120303. The next prime is 21521120329. The reversal of 21521120315 is 51302112512.

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

It is a cyclic number.

It is not a de Polignac number, because 21521120315 - 2²⁴ = 21504343099 is a prime.

It is a super-2 number, since 2×21521120315² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2152112027 + ... + 2152112036.

It is an arithmetic number, because the mean of its divisors is an integer number (6456336096).

Almost surely, 2^21521120315 is an apocalyptic number.

21521120315 is a deficient number, since it is larger than the sum of its proper divisors (4304224069).

21521120315 is an equidigital number, since it uses as much as digits as its factorization.

21521120315 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4304224068.

The product of its (nonzero) digits is 600, while the sum is 23.

Adding to 21521120315 its reverse (51302112512), we get a palindrome (72823232827).

The spelling of 21521120315 in words is "twenty-one billion, five hundred twenty-one million, one hundred twenty thousand, three hundred fifteen".