21375225 has 24 divisors (see below), whose sum is σ = 39268320. Its totient is φ = 11399760.

The previous prime is 21375223. The next prime is 21375241. The reversal of 21375225 is 52257312.

21375225 is a `hidden beast` number, since 2 + 137 + 522 + 5 = 666.

It is not a de Polignac number, because 21375225 - 2¹ = 21375223 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21375223) 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, 15159 + ... + 16508.

It is an arithmetic number, because the mean of its divisors is an integer number (1636180).

Almost surely, 2^21375225 is an apocalyptic number.

21375225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21375225 is a deficient number, since it is larger than the sum of its proper divisors (17893095).

21375225 is a wasteful number, since it uses less digits than its factorization.

21375225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31686 (or 31675 counting only the distinct ones).

The product of its digits is 4200, while the sum is 27.

The square root of 21375225 is about 4623.3348353759. The cubic root of 21375225 is about 277.5259289139.

The spelling of 21375225 in words is "twenty-one million, three hundred seventy-five thousand, two hundred twenty-five".