21380913 has 12 divisors (see below), whose sum is σ = 30924660. Its totient is φ = 14234976.

The previous prime is 21380893. The next prime is 21380921. The reversal of 21380913 is 31908312.

It can be written as a sum of positive squares in 2 ways, for example, as 18766224 + 2614689 = 4332^2 + 1617^2 .

It is not a de Polignac number, because 21380913 - 2⁵ = 21380881 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21380923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10095 + ... + 12027.

It is an arithmetic number, because the mean of its divisors is an integer number (2577055).

Almost surely, 2^21380913 is an apocalyptic number.

It is an amenable number.

21380913 is a deficient number, since it is larger than the sum of its proper divisors (9543747).

21380913 is a wasteful number, since it uses less digits than its factorization.

21380913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3168 (or 3165 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 21380913 is about 4623.9499348501. The cubic root of 21380913 is about 277.5505435084.

The spelling of 21380913 in words is "twenty-one million, three hundred eighty thousand, nine hundred thirteen".