21003020 has 12 divisors (see below), whose sum is σ = 44106384. Its totient is φ = 8401200.

The previous prime is 21003011. The next prime is 21003053. The reversal of 21003020 is 2030012.

It is a super-2 number, since 2×21003020² = 882253698240800, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21002989 and 21003007.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 525056 + ... + 525095.

It is an arithmetic number, because the mean of its divisors is an integer number (3675532).

Almost surely, 2^21003020 is an apocalyptic number.

21003020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21003020 is an abundant number, since it is smaller than the sum of its proper divisors (23103364).

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

21003020 is a wasteful number, since it uses less digits than its factorization.

21003020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1050160 (or 1050158 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 8.

The square root of 21003020 is about 4582.9051921243. The cubic root of 21003020 is about 275.9056423233.

Adding to 21003020 its reverse (2030012), we get a palindrome (23033032).

The spelling of 21003020 in words is "twenty-one million, three thousand, twenty".