21630513 has 8 divisors (see below), whose sum is σ = 29068288. Its totient is φ = 14306544.

The previous prime is 21630487. The next prime is 21630517. The reversal of 21630513 is 31503612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21630513 - 2²⁰ = 20581937 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21630513.

It is not an unprimeable number, because it can be changed into a prime (21630517) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28006 + ... + 28767.

It is an arithmetic number, because the mean of its divisors is an integer number (3633536).

Almost surely, 2^21630513 is an apocalyptic number.

It is an amenable number.

21630513 is a deficient number, since it is larger than the sum of its proper divisors (7437775).

21630513 is a wasteful number, since it uses less digits than its factorization.

21630513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56903.

The product of its (nonzero) digits is 540, while the sum is 21.

The square root of 21630513 is about 4650.8615330926. The cubic root of 21630513 is about 278.6264060929.

The spelling of 21630513 in words is "twenty-one million, six hundred thirty thousand, five hundred thirteen".