21603073 has 8 divisors (see below), whose sum is σ = 22938120. Its totient is φ = 20275200.

The previous prime is 21603053. The next prime is 21603077. The reversal of 21603073 is 37030612.

It can be written as a sum of positive squares in 4 ways, for example, as 16459249 + 5143824 = 4057^2 + 2268^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21603073 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21603077) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5233 + ... + 8401.

It is an arithmetic number, because the mean of its divisors is an integer number (2867265).

Almost surely, 2^21603073 is an apocalyptic number.

It is an amenable number.

21603073 is a deficient number, since it is larger than the sum of its proper divisors (1335047).

21603073 is a wasteful number, since it uses less digits than its factorization.

21603073 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3587.

The product of its (nonzero) digits is 756, while the sum is 22.

The square root of 21603073 is about 4647.9106058529. The cubic root of 21603073 is about 278.5085364298.

Adding to 21603073 its reverse (37030612), we get a palindrome (58633685).

The spelling of 21603073 in words is "twenty-one million, six hundred three thousand, seventy-three".