21451145 has 8 divisors (see below), whose sum is σ = 25853256. Its totient is φ = 17086336.

The previous prime is 21451141. The next prime is 21451147. The reversal of 21451145 is 54115412.

It can be written as a sum of positive squares in 4 ways, for example, as 32761 + 21418384 = 181^2 + 4628^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21451145 - 2² = 21451141 is a prime.

It is a super-2 number, since 2×21451145² = 920303243622050, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21451145.

It is not an unprimeable number, because it can be changed into a prime (21451141) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 8042 + ... + 10371.

It is an arithmetic number, because the mean of its divisors is an integer number (3231657).

Almost surely, 2^21451145 is an apocalyptic number.

It is an amenable number.

21451145 is a deficient number, since it is larger than the sum of its proper divisors (4402111).

21451145 is a wasteful number, since it uses less digits than its factorization.

21451145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18651.

The product of its digits is 800, while the sum is 23.

The square root of 21451145 is about 4631.5380814585. The cubic root of 21451145 is about 277.8541106071.

Adding to 21451145 its reverse (54115412), we get a palindrome (75566557).

The spelling of 21451145 in words is "twenty-one million, four hundred fifty-one thousand, one hundred forty-five".