21125445 has 16 divisors (see below), whose sum is σ = 36873792. Its totient is φ = 10242560.

The previous prime is 21125443. The next prime is 21125471. The reversal of 21125445 is 54452112.

It is not a de Polignac number, because 21125445 - 2¹ = 21125443 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21125443) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 63852 + ... + 64181.

It is an arithmetic number, because the mean of its divisors is an integer number (2304612).

Almost surely, 2^21125445 is an apocalyptic number.

It is an amenable number.

21125445 is a deficient number, since it is larger than the sum of its proper divisors (15748347).

21125445 is a wasteful number, since it uses less digits than its factorization.

21125445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128052.

The product of its digits is 1600, while the sum is 24.

The square root of 21125445 is about 4596.2424870757. The cubic root of 21125445 is about 276.4406817392.

Adding to 21125445 its reverse (54452112), we get a palindrome (75577557).

It can be divided in two parts, 2112 and 5445, that added together give a palindrome (7557).

The spelling of 21125445 in words is "twenty-one million, one hundred twenty-five thousand, four hundred forty-five".