21355625 has 20 divisors (see below), whose sum is σ = 27291264. Its totient is φ = 16698000.

The previous prime is 21355591. The next prime is 21355627. The reversal of 21355625 is 52655312.

It is a happy number.

It is not a de Polignac number, because 21355625 - 2⁶ = 21355561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21355627) by changing a digit.

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 19 ways as a sum of consecutive naturals, for example, 29012 + ... + 29738.

Almost surely, 2^21355625 is an apocalyptic number.

21355625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21355625 is a deficient number, since it is larger than the sum of its proper divisors (5935639).

21355625 is an frugal number, since it uses more digits than its factorization.

21355625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 794 (or 779 counting only the distinct ones).

The product of its digits is 9000, while the sum is 29.

The square root of 21355625 is about 4621.2146671627. The cubic root of 21355625 is about 277.4410772279.

The spelling of 21355625 in words is "twenty-one million, three hundred fifty-five thousand, six hundred twenty-five".