21001345 has 8 divisors (see below), whose sum is σ = 25629120. Its totient is φ = 16516080.

The previous prime is 21001319. The next prime is 21001349. The reversal of 21001345 is 54310012.

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

It is not a de Polignac number, because 21001345 - 2¹⁹ = 20477057 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21001349) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35301 + ... + 35890.

It is an arithmetic number, because the mean of its divisors is an integer number (3203640).

Almost surely, 2^21001345 is an apocalyptic number.

It is an amenable number.

21001345 is a deficient number, since it is larger than the sum of its proper divisors (4627775).

21001345 is an equidigital number, since it uses as much as digits as its factorization.

21001345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71255.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21001345 is about 4582.7224441373. The cubic root of 21001345 is about 275.8983075965.

Adding to 21001345 its reverse (54310012), we get a palindrome (75311357).

The spelling of 21001345 in words is "twenty-one million, one thousand, three hundred forty-five".