21025020 has 48 divisors (see below), whose sum is σ = 61971840. Its totient is φ = 5311296.

The previous prime is 21025019. The next prime is 21025021. The reversal of 21025020 is 2052012.

It is an interprime number because it is at equal distance from previous prime (21025019) and next prime (21025021).

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 = 21024987 and 21025005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21025021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8082 + ... + 10361.

It is an arithmetic number, because the mean of its divisors is an integer number (1291080).

Almost surely, 2^21025020 is an apocalyptic number.

21025020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21025020 is an abundant number, since it is smaller than the sum of its proper divisors (40946820).

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

21025020 is a wasteful number, since it uses less digits than its factorization.

21025020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18474 (or 18472 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 12.

The square root of 21025020 is about 4585.3047881248. The cubic root of 21025020 is about 276.0019428555.

Adding to 21025020 its reverse (2052012), we get a palindrome (23077032).

The spelling of 21025020 in words is "twenty-one million, twenty-five thousand, twenty".