21370645 has 16 divisors (see below), whose sum is σ = 26725248. Its totient is φ = 16390080.

The previous prime is 21370639. The next prime is 21370667. The reversal of 21370645 is 54607312.

It is not a de Polignac number, because 21370645 - 2⁹ = 21370133 is a prime.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 12322 + ... + 13948.

It is an arithmetic number, because the mean of its divisors is an integer number (1670328).

Almost surely, 2^21370645 is an apocalyptic number.

It is an amenable number.

21370645 is a deficient number, since it is larger than the sum of its proper divisors (5354603).

21370645 is a wasteful number, since it uses less digits than its factorization.

21370645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1740.

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 21370645 is about 4622.8394953751. The cubic root of 21370645 is about 277.5061059718.

Adding to 21370645 its reverse (54607312), we get a palindrome (75977957).

The spelling of 21370645 in words is "twenty-one million, three hundred seventy thousand, six hundred forty-five".