21003073 has 16 divisors (see below), whose sum is σ = 25958016. Its totient is φ = 16548480.

The previous prime is 21003053. The next prime is 21003079. The reversal of 21003073 is 37030012.

It is a de Polignac number, because none of the positive numbers 2^k-21003073 is a prime.

It is a super-2 number, since 2×21003073² = 882258150886658, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21003079) 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, 40053 + ... + 40573.

It is an arithmetic number, because the mean of its divisors is an integer number (1622376).

Almost surely, 2^21003073 is an apocalyptic number.

It is an amenable number.

21003073 is a deficient number, since it is larger than the sum of its proper divisors (4954943).

21003073 is a wasteful number, since it uses less digits than its factorization.

21003073 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 984.

The product of its (nonzero) digits is 126, while the sum is 16.

The square root of 21003073 is about 4582.9109744790. The cubic root of 21003073 is about 275.9058744008.

Adding to 21003073 its reverse (37030012), we get a palindrome (58033085).

The spelling of 21003073 in words is "twenty-one million, three thousand, seventy-three".