21523320415 has 4 divisors (see below), whose sum is σ = 25827984504. Its totient is φ = 17218656328.

The previous prime is 21523320409. The next prime is 21523320421. The reversal of 21523320415 is 51402332512.

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

It is an interprime number because it is at equal distance from previous prime (21523320409) and next prime (21523320421).

It is a cyclic number.

It is not a de Polignac number, because 21523320415 - 2⁵ = 21523320383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2152332037 + ... + 2152332046.

It is an arithmetic number, because the mean of its divisors is an integer number (6456996126).

Almost surely, 2^21523320415 is an apocalyptic number.

21523320415 is a deficient number, since it is larger than the sum of its proper divisors (4304664089).

21523320415 is an equidigital number, since it uses as much as digits as its factorization.

21523320415 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4304664088.

The product of its (nonzero) digits is 7200, while the sum is 28.

Adding to 21523320415 its reverse (51402332512), we get a palindrome (72925652927).

The spelling of 21523320415 in words is "twenty-one billion, five hundred twenty-three million, three hundred twenty thousand, four hundred fifteen".