21555045 has 16 divisors (see below), whose sum is σ = 38320320. Its totient is φ = 11495952.

The previous prime is 21555041. The next prime is 21555067. The reversal of 21555045 is 54055512.

21555045 is a `hidden beast` number, since 2 + 155 + 504 + 5 = 666.

It is not a de Polignac number, because 21555045 - 2² = 21555041 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21555041) 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 15 ways as a sum of consecutive naturals, for example, 79699 + ... + 79968.

It is an arithmetic number, because the mean of its divisors is an integer number (2395020).

Almost surely, 2^21555045 is an apocalyptic number.

It is an amenable number.

21555045 is a deficient number, since it is larger than the sum of its proper divisors (16765275).

21555045 is a wasteful number, since it uses less digits than its factorization.

21555045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159681 (or 159675 counting only the distinct ones).

The product of its (nonzero) digits is 5000, while the sum is 27.

The square root of 21555045 is about 4642.7411084401. The cubic root of 21555045 is about 278.3019896896.

The spelling of 21555045 in words is "twenty-one million, five hundred fifty-five thousand, forty-five".