21517625 has 16 divisors (see below), whose sum is σ = 27206400. Its totient is φ = 16988400.

The previous prime is 21517621. The next prime is 21517649. The reversal of 21517625 is 52671512.

It is not a de Polignac number, because 21517625 - 2² = 21517621 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21517621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8786 + ... + 10964.

It is an arithmetic number, because the mean of its divisors is an integer number (1700400).

Almost surely, 2^21517625 is an apocalyptic number.

21517625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21517625 is a deficient number, since it is larger than the sum of its proper divisors (5688775).

21517625 is an equidigital number, since it uses as much as digits as its factorization.

21517625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2273 (or 2263 counting only the distinct ones).

The product of its digits is 4200, while the sum is 29.

The square root of 21517625 is about 4638.7094110323. The cubic root of 21517625 is about 278.1408504201.

The spelling of 21517625 in words is "twenty-one million, five hundred seventeen thousand, six hundred twenty-five".