21000125 has 16 divisors (see below), whose sum is σ = 26824512. Its totient is φ = 16405200.

The previous prime is 21000121. The next prime is 21000131. The reversal of 21000125 is 52100012.

It is not a de Polignac number, because 21000125 - 2² = 21000121 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000121) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3422 + ... + 7328.

It is an arithmetic number, because the mean of its divisors is an integer number (1676532).

Almost surely, 2^21000125 is an apocalyptic number.

21000125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21000125 is a deficient number, since it is larger than the sum of its proper divisors (5824387).

21000125 is an equidigital number, since it uses as much as digits as its factorization.

21000125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3965 (or 3955 counting only the distinct ones).

The product of its (nonzero) digits is 20, while the sum is 11.

The square root of 21000125 is about 4582.5893335537. The cubic root of 21000125 is about 275.8929650426.

Adding to 21000125 its reverse (52100012), we get a palindrome (73100137).

The spelling of 21000125 in words is "twenty-one million, one hundred twenty-five", and thus it is an aban number.