21520040315 has 4 divisors (see below), whose sum is σ = 25824048384. Its totient is φ = 17216032248.

The previous prime is 21520040309. The next prime is 21520040317. The reversal of 21520040315 is 51304002512.

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 21520040315 - 2¹⁸ = 21519778171 is a prime.

It is a super-2 number, since 2×21520040315² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21520040317) 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, 2152004027 + ... + 2152004036.

It is an arithmetic number, because the mean of its divisors is an integer number (6456012096).

Almost surely, 2^21520040315 is an apocalyptic number.

21520040315 is a deficient number, since it is larger than the sum of its proper divisors (4304008069).

21520040315 is an equidigital number, since it uses as much as digits as its factorization.

21520040315 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4304008068.

The product of its (nonzero) digits is 1200, while the sum is 23.

Adding to 21520040315 its reverse (51304002512), we get a palindrome (72824042827).

The spelling of 21520040315 in words is "twenty-one billion, five hundred twenty million, forty thousand, three hundred fifteen".