21007020 has 48 divisors (see below), whose sum is σ = 60852960. Its totient is φ = 5408256.

The previous prime is 21007013. The next prime is 21007067. The reversal of 21007020 is 2070012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21006987 and 21007005.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4297 + ... + 7776.

It is an arithmetic number, because the mean of its divisors is an integer number (1267770).

Almost surely, 2^21007020 is an apocalyptic number.

21007020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21007020 is an abundant number, since it is smaller than the sum of its proper divisors (39845940).

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

21007020 is a wasteful number, since it uses less digits than its factorization.

21007020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12114 (or 12112 counting only the distinct ones).

The product of its (nonzero) digits is 28, while the sum is 12.

The square root of 21007020 is about 4583.3415757502. The cubic root of 21007020 is about 275.9231565111.

Adding to 21007020 its reverse (2070012), we get a palindrome (23077032).

The spelling of 21007020 in words is "twenty-one million, seven thousand, twenty".