21100513 has 8 divisors (see below), whose sum is σ = 24264128. Its totient is φ = 17974224.

The previous prime is 21100489. The next prime is 21100517. The reversal of 21100513 is 31500112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21100513 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21100493 and 21100502.

It is not an unprimeable number, because it can be changed into a prime (21100517) 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, 8106 + ... + 10387.

It is an arithmetic number, because the mean of its divisors is an integer number (3033016).

Almost surely, 2^21100513 is an apocalyptic number.

It is an amenable number.

21100513 is a deficient number, since it is larger than the sum of its proper divisors (3163615).

21100513 is a wasteful number, since it uses less digits than its factorization.

21100513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18663.

The product of its (nonzero) digits is 30, while the sum is 13.

The square root of 21100513 is about 4593.5294708971. The cubic root of 21100513 is about 276.3318882561.

Adding to 21100513 its reverse (31500112), we get a palindrome (52600625).

The spelling of 21100513 in words is "twenty-one million, one hundred thousand, five hundred thirteen".