21028125 has 24 divisors (see below), whose sum is σ = 35060256. Its totient is φ = 11210000.

The previous prime is 21028123. The next prime is 21028127. The reversal of 21028125 is 52182012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21028123) and next prime (21028127).

It is not a de Polignac number, because 21028125 - 2¹ = 21028123 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21028123) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8254 + ... + 10496.

It is an arithmetic number, because the mean of its divisors is an integer number (1460844).

Almost surely, 2^21028125 is an apocalyptic number.

21028125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21028125 is a deficient number, since it is larger than the sum of its proper divisors (14032131).

21028125 is an frugal number, since it uses more digits than its factorization.

21028125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2271 (or 2251 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 21028125 is about 4585.6433572619. The cubic root of 21028125 is about 276.0155289519.

The spelling of 21028125 in words is "twenty-one million, twenty-eight thousand, one hundred twenty-five".