21030913 has 8 divisors (see below), whose sum is σ = 21593088. Its totient is φ = 20472144.

The previous prime is 21030899. The next prime is 21030923. The reversal of 21030913 is 31903012.

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

It is a cyclic number.

It is not a de Polignac number, because 21030913 - 2⁵ = 21030881 is a prime.

It is a super-2 number, since 2×21030913² = 884598603227138, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21030923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15831 + ... + 17107.

It is an arithmetic number, because the mean of its divisors is an integer number (2699136).

Almost surely, 2^21030913 is an apocalyptic number.

It is an amenable number.

21030913 is a deficient number, since it is larger than the sum of its proper divisors (562175).

21030913 is a wasteful number, since it uses less digits than its factorization.

21030913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1703.

The product of its (nonzero) digits is 162, while the sum is 19.

The square root of 21030913 is about 4585.9473394273. The cubic root of 21030913 is about 276.0277268581.

Adding to 21030913 its reverse (31903012), we get a palindrome (52933925).

The spelling of 21030913 in words is "twenty-one million, thirty thousand, nine hundred thirteen".