21555245 has 8 divisors (see below), whose sum is σ = 26231040. Its totient is φ = 17001040.

The previous prime is 21555223. The next prime is 21555263. The reversal of 21555245 is 54255512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21555245 - 2⁶ = 21555181 is a prime.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 30005 + ... + 30714.

It is an arithmetic number, because the mean of its divisors is an integer number (3278880).

Almost surely, 2^21555245 is an apocalyptic number.

It is an amenable number.

21555245 is a deficient number, since it is larger than the sum of its proper divisors (4675795).

21555245 is an equidigital number, since it uses as much as digits as its factorization.

21555245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60795.

The product of its digits is 10000, while the sum is 29.

The square root of 21555245 is about 4642.7626473900. The cubic root of 21555245 is about 278.3028504351.

The spelling of 21555245 in words is "twenty-one million, five hundred fifty-five thousand, two hundred forty-five".