21238913 has 8 divisors (see below), whose sum is σ = 22444800. Its totient is φ = 20056608.

The previous prime is 21238901. The next prime is 21238939. The reversal of 21238913 is 31983212.

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 21238913 - 2¹² = 21234817 is a prime.

It is a super-5 number, since 5×21238913⁵ (a number of 38 digits) contains 55555 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21238963) 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, 4028 + ... + 7661.

It is an arithmetic number, because the mean of its divisors is an integer number (2805600).

Almost surely, 2^21238913 is an apocalyptic number.

21238913 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21238913 is a deficient number, since it is larger than the sum of its proper divisors (1205887).

21238913 is a wasteful number, since it uses less digits than its factorization.

21238913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11791.

The product of its digits is 2592, while the sum is 29.

The square root of 21238913 is about 4608.5695177571. The cubic root of 21238913 is about 276.9347333274.

The spelling of 21238913 in words is "twenty-one million, two hundred thirty-eight thousand, nine hundred thirteen".