21230745 has 16 divisors (see below), whose sum is σ = 34527552. Its totient is φ = 11136960.

The previous prime is 21230719. The next prime is 21230749. The reversal of 21230745 is 54703212.

It is not a de Polignac number, because 21230745 - 2⁷ = 21230617 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21230749) 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 15 ways as a sum of consecutive naturals, for example, 10687 + ... + 12516.

It is an arithmetic number, because the mean of its divisors is an integer number (2157972).

Almost surely, 2^21230745 is an apocalyptic number.

It is an amenable number.

21230745 is a deficient number, since it is larger than the sum of its proper divisors (13296807).

21230745 is a wasteful number, since it uses less digits than its factorization.

21230745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23272.

The product of its (nonzero) digits is 1680, while the sum is 24.

The square root of 21230745 is about 4607.6832573431. The cubic root of 21230745 is about 276.8992278547.

Adding to 21230745 its reverse (54703212), we get a palindrome (75933957).

The spelling of 21230745 in words is "twenty-one million, two hundred thirty thousand, seven hundred forty-five".