21006371 has 8 divisors (see below), whose sum is σ = 21331200. Its totient is φ = 20684160.

The previous prime is 21006341. The next prime is 21006379. The reversal of 21006371 is 17360012.

It is a happy number.

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 21006371 - 2¹⁴ = 20989987 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21006379) 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, 20315 + ... + 21323.

It is an arithmetic number, because the mean of its divisors is an integer number (2666400).

Almost surely, 2^21006371 is an apocalyptic number.

21006371 is a deficient number, since it is larger than the sum of its proper divisors (324829).

21006371 is a wasteful number, since it uses less digits than its factorization.

21006371 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1309.

The product of its (nonzero) digits is 252, while the sum is 20.

The square root of 21006371 is about 4583.2707753306. The cubic root of 21006371 is about 275.9203149853.

Adding to 21006371 its reverse (17360012), we get a palindrome (38366383).

The spelling of 21006371 in words is "twenty-one million, six thousand, three hundred seventy-one".