21375025 has 18 divisors (see below), whose sum is σ = 30834150. Its totient is φ = 14656320.

The previous prime is 21375023. The next prime is 21375031. The reversal of 21375025 is 52057312.

It can be written as a sum of positive squares in 3 ways, for example, as 6927424 + 14447601 = 2632^2 + 3801^2 .

It is not a de Polignac number, because 21375025 - 2¹ = 21375023 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is not an unprimeable number, because it can be changed into a prime (21375023) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 7500 + ... + 9949.

Almost surely, 2^21375025 is an apocalyptic number.

21375025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21375025 is a deficient number, since it is larger than the sum of its proper divisors (9459125).

21375025 is a wasteful number, since it uses less digits than its factorization.

21375025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17473 (or 17461 counting only the distinct ones).

The product of its (nonzero) digits is 2100, while the sum is 25.

The square root of 21375025 is about 4623.3132059163. The cubic root of 21375025 is about 277.5250633424.

The spelling of 21375025 in words is "twenty-one million, three hundred seventy-five thousand, twenty-five".