21003012 has 18 divisors (see below), whose sum is σ = 53091038. Its totient is φ = 7000992.

The previous prime is 21003011. The next prime is 21003053. The reversal of 21003012 is 21030012.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 20575296 + 427716 = 4536^2 + 654^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-2 number, since 2×21003012² = 882253026144288, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21002985 and 21003003.

It is not an unprimeable number, because it can be changed into a prime (21003011) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 291673 + ... + 291744.

Almost surely, 2^21003012 is an apocalyptic number.

It is an amenable number.

21003012 is an abundant number, since it is smaller than the sum of its proper divisors (32088026).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21003012 is a wasteful number, since it uses less digits than its factorization.

21003012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 583427 (or 583422 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 21003012 is about 4582.9043193154. The cubic root of 21003012 is about 275.9056072927.

Adding to 21003012 its reverse (21030012), we get a palindrome (42033024).

Subtracting 21003012 from its reverse (21030012), we obtain a cube (27000 = 30³).

The spelling of 21003012 in words is "twenty-one million, three thousand, twelve".