21255125 has 16 divisors (see below), whose sum is σ = 26815152. Its totient is φ = 16819200.

The previous prime is 21255107. The next prime is 21255127. The reversal of 21255125 is 52155212.

It can be written as a sum of positive squares in 8 ways, for example, as 13845841 + 7409284 = 3721^2 + 2722^2 .

It is not a de Polignac number, because 21255125 - 2⁶ = 21255061 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21255125.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21255127) 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, 11249 + ... + 13001.

It is an arithmetic number, because the mean of its divisors is an integer number (1675947).

Almost surely, 2^21255125 is an apocalyptic number.

21255125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21255125 is a deficient number, since it is larger than the sum of its proper divisors (5560027).

21255125 is an equidigital number, since it uses as much as digits as its factorization.

21255125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1865 (or 1855 counting only the distinct ones).

The product of its digits is 1000, while the sum is 23.

The square root of 21255125 is about 4610.3280794321. The cubic root of 21255125 is about 277.0051783016.

The spelling of 21255125 in words is "twenty-one million, two hundred fifty-five thousand, one hundred twenty-five".