21503073 has 8 divisors (see below), whose sum is σ = 28699936. Its totient is φ = 14320800.

The previous prime is 21503071. The next prime is 21503093. The reversal of 21503073 is 37030512.

It is a happy number.

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

It is not a de Polignac number, because 21503073 - 2¹ = 21503071 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21503071) 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, 453 + ... + 6573.

It is an arithmetic number, because the mean of its divisors is an integer number (3587492).

Almost surely, 2^21503073 is an apocalyptic number.

It is an amenable number.

21503073 is a deficient number, since it is larger than the sum of its proper divisors (7196863).

21503073 is a wasteful number, since it uses less digits than its factorization.

21503073 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7295.

The product of its (nonzero) digits is 630, while the sum is 21.

The square root of 21503073 is about 4637.1406060201. The cubic root of 21503073 is about 278.0781356547.

Adding to 21503073 its reverse (37030512), we get a palindrome (58533585).

The spelling of 21503073 in words is "twenty-one million, five hundred three thousand, seventy-three".