21000634513 has 4 divisors (see below), whose sum is σ = 21678074368. Its totient is φ = 20323194660.

The previous prime is 21000634489. The next prime is 21000634537. The reversal of 21000634513 is 31543600012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (21000634489) and next prime (21000634537).

It is a cyclic number.

It is not a de Polignac number, because 21000634513 - 2⁹ = 21000634001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21000634553) 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, 338719881 + ... + 338719942.

It is an arithmetic number, because the mean of its divisors is an integer number (5419518592).

Almost surely, 2^21000634513 is an apocalyptic number.

It is an amenable number.

21000634513 is a deficient number, since it is larger than the sum of its proper divisors (677439855).

21000634513 is an equidigital number, since it uses as much as digits as its factorization.

21000634513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 677439854.

The product of its (nonzero) digits is 2160, while the sum is 25.

The spelling of 21000634513 in words is "twenty-one billion, six hundred thirty-four thousand, five hundred thirteen".