21379643 has 8 divisors (see below), whose sum is σ = 21947376. Its totient is φ = 20815200.

The previous prime is 21379619. The next prime is 21379663. The reversal of 21379643 is 34697312.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21379643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21379663) 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 7 ways as a sum of consecutive naturals, for example, 17513 + ... + 18693.

It is an arithmetic number, because the mean of its divisors is an integer number (2743422).

Almost surely, 2^21379643 is an apocalyptic number.

21379643 is a deficient number, since it is larger than the sum of its proper divisors (567733).

21379643 is a wasteful number, since it uses less digits than its factorization.

21379643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1645.

The product of its digits is 27216, while the sum is 35.

The square root of 21379643 is about 4623.8126043342. The cubic root of 21379643 is about 277.5450480123.

It can be divided in two parts, 21379 and 643, that added together give a palindrome (22022).

The spelling of 21379643 in words is "twenty-one million, three hundred seventy-nine thousand, six hundred forty-three".