21003072 has 28 divisors (see below), whose sum is σ = 55571136. Its totient is φ = 7000960.

The previous prime is 21003053. The next prime is 21003079. The reversal of 21003072 is 27030012.

It is a super-2 number, since 2×21003072² = 882258066874368, which contains 22 as substring.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 54504 + ... + 54887.

Almost surely, 2^21003072 is an apocalyptic number.

It is an amenable number.

21003072 is an abundant number, since it is smaller than the sum of its proper divisors (34568064).

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

21003072 is a wasteful number, since it uses less digits than its factorization.

21003072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109406 (or 109396 counting only the distinct ones).

The product of its (nonzero) digits is 84, while the sum is 15.

The square root of 21003072 is about 4582.9108653780. The cubic root of 21003072 is about 275.9058700220.

Adding to 21003072 its reverse (27030012), we get a palindrome (48033084).

The spelling of 21003072 in words is "twenty-one million, three thousand, seventy-two".