21001893 has 8 divisors (see below), whose sum is σ = 30548256. Its totient is φ = 12728400.

The previous prime is 21001889. The next prime is 21001909. The reversal of 21001893 is 39810012.

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

It is not a de Polignac number, because 21001893 - 2² = 21001889 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 318178 + ... + 318243.

It is an arithmetic number, because the mean of its divisors is an integer number (3818532).

Almost surely, 2^21001893 is an apocalyptic number.

It is an amenable number.

21001893 is a deficient number, since it is larger than the sum of its proper divisors (9546363).

21001893 is a wasteful number, since it uses less digits than its factorization.

21001893 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 636435.

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 21001893 is about 4582.7822335346. The cubic root of 21001893 is about 275.9007072993.

It can be divided in two parts, 2100 and 1893, that added together give a palindrome (3993).

The spelling of 21001893 in words is "twenty-one million, one thousand, eight hundred ninety-three".