21515630573 has 4 divisors (see below), whose sum is σ = 22097134140. Its totient is φ = 20934127008.

The previous prime is 21515630519. The next prime is 21515630659. The reversal of 21515630573 is 37503651512.

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

It can be written as a sum of positive squares in 2 ways, for example, as 14844498244 + 6671132329 = 121838^2 + 81677^2 .

It is a cyclic number.

It is not a de Polignac number, because 21515630573 - 2¹⁰ = 21515629549 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 (21515630173) 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, 290751728 + ... + 290751801.

It is an arithmetic number, because the mean of its divisors is an integer number (5524283535).

Almost surely, 2^21515630573 is an apocalyptic number.

It is an amenable number.

21515630573 is a deficient number, since it is larger than the sum of its proper divisors (581503567).

21515630573 is an equidigital number, since it uses as much as digits as its factorization.

21515630573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 581503566.

The product of its (nonzero) digits is 94500, while the sum is 38.

The spelling of 21515630573 in words is "twenty-one billion, five hundred fifteen million, six hundred thirty thousand, five hundred seventy-three".