21389125 has 16 divisors (see below), whose sum is σ = 26910000. Its totient is φ = 16972800.

The previous prime is 21389119. The next prime is 21389141. The reversal of 21389125 is 52198312.

It can be written as a sum of positive squares in 8 ways, for example, as 6964321 + 14424804 = 2639^2 + 3798^2 .

It is not a de Polignac number, because 21389125 - 2¹¹ = 21387077 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16501 + ... + 17749.

It is an arithmetic number, because the mean of its divisors is an integer number (1681875).

Almost surely, 2^21389125 is an apocalyptic number.

21389125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21389125 is a deficient number, since it is larger than the sum of its proper divisors (5520875).

21389125 is a wasteful number, since it uses less digits than its factorization.

21389125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1401 (or 1391 counting only the distinct ones).

The product of its digits is 4320, while the sum is 31.

The square root of 21389125 is about 4624.8378349949. The cubic root of 21389125 is about 277.5860729129.

The spelling of 21389125 in words is "twenty-one million, three hundred eighty-nine thousand, one hundred twenty-five".