21025000 has 72 divisors (see below), whose sum is σ = 51031890. Its totient is φ = 8120000.

The previous prime is 21024961. The next prime is 21025019. The reversal of 21025000 is 52012.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 9 ways, for example, as 9205156 + 11819844 = 3034^2 + 3438^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 724986 + ... + 725014.

Almost surely, 2^21025000 is an apocalyptic number.

21025000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21025000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25515945).

21025000 is an abundant number, since it is smaller than the sum of its proper divisors (30006890).

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

21025000 is an frugal number, since it uses more digits than its factorization.

21025000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89 (or 36 counting only the distinct ones).

The product of its (nonzero) digits is 20, while the sum is 10.

The square root of 21025000 is about 4585.3026072442. The cubic root of 21025000 is about 276.0018553400.

Multiplying 21025000 by its sum of digits (10), we get a square (210250000 = 14500²).

21025000 divided by its sum of digits (10) gives a square (2102500 = 1450²).

Adding to 21025000 its reverse (52012), we get a palindrome (21077012).

The spelling of 21025000 in words is "twenty-one million, twenty-five thousand".