21320045 has 16 divisors (see below), whose sum is σ = 26687232. Its totient is φ = 16336320.

The previous prime is 21320021. The next prime is 21320051. The reversal of 21320045 is 54002312.

It is not a de Polignac number, because 21320045 - 2⁶ = 21319981 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10460 + ... + 12330.

It is an arithmetic number, because the mean of its divisors is an integer number (1667952).

Almost surely, 2^21320045 is an apocalyptic number.

It is an amenable number.

21320045 is a deficient number, since it is larger than the sum of its proper divisors (5367187).

21320045 is a wasteful number, since it uses less digits than its factorization.

21320045 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1972.

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 21320045 is about 4617.3634251594. The cubic root of 21320045 is about 277.2869126814.

Adding to 21320045 its reverse (54002312), we get a palindrome (75322357).

The spelling of 21320045 in words is "twenty-one million, three hundred twenty thousand, forty-five".