21013003 has 16 divisors (see below), whose sum is σ = 24935904. Its totient is φ = 17487360.

The previous prime is 21012997. The next prime is 21013019. The reversal of 21013003 is 30031012.

It is not a de Polignac number, because 21013003 - 2¹³ = 21004811 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21013043) 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, 5401 + ... + 8437.

It is an arithmetic number, because the mean of its divisors is an integer number (1558494).

Almost surely, 2^21013003 is an apocalyptic number.

21013003 is a deficient number, since it is larger than the sum of its proper divisors (3922901).

21013003 is a wasteful number, since it uses less digits than its factorization.

21013003 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3102.

The product of its (nonzero) digits is 18, while the sum is 10.

The square root of 21013003 is about 4583.9942190190. The cubic root of 21013003 is about 275.9493492084.

Adding to 21013003 its reverse (30031012), we get a palindrome (51044015).

Subtracting 21013003 from its reverse (30031012), we obtain a square (9018009 = 3003²).

The spelling of 21013003 in words is "twenty-one million, thirteen thousand, three".