21553625 has 16 divisors (see below), whose sum is σ = 27041040. Its totient is φ = 17152000.

The previous prime is 21553613. The next prime is 21553627. The reversal of 21553625 is 52635512.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 7573504 + 13980121 = 2752^2 + 3739^2 .

It is not a de Polignac number, because 21553625 - 2¹² = 21549529 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21553627) 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, 33305 + ... + 33945.

It is an arithmetic number, because the mean of its divisors is an integer number (1690065).

Almost surely, 2^21553625 is an apocalyptic number.

21553625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21553625 is a deficient number, since it is larger than the sum of its proper divisors (5487415).

21553625 is an equidigital number, since it uses as much as digits as its factorization.

21553625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 925 (or 915 counting only the distinct ones).

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

The square root of 21553625 is about 4642.5881790226. The cubic root of 21553625 is about 278.2958782433.

The spelling of 21553625 in words is "twenty-one million, five hundred fifty-three thousand, six hundred twenty-five".