21021513 has 16 divisors (see below), whose sum is σ = 28946880. Its totient is φ = 13559616.

The previous prime is 21021499. The next prime is 21021529. The reversal of 21021513 is 31512012.

It is not a de Polignac number, because 21021513 - 2⁶ = 21021449 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21021492 and 21021501.

It is not an unprimeable number, because it can be changed into a prime (21021713) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25006 + ... + 25832.

It is an arithmetic number, because the mean of its divisors is an integer number (1809180).

Almost surely, 2^21021513 is an apocalyptic number.

It is an amenable number.

21021513 is a deficient number, since it is larger than the sum of its proper divisors (7925367).

21021513 is a wasteful number, since it uses less digits than its factorization.

21021513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1096.

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 21021513 is about 4584.9223548496. The cubic root of 21021513 is about 275.9865961775.

Adding to 21021513 its reverse (31512012), we get a palindrome (52533525).

The spelling of 21021513 in words is "twenty-one million, twenty-one thousand, five hundred thirteen".