21055305 has 32 divisors (see below), whose sum is σ = 35280000. Its totient is φ = 10708992.

The previous prime is 21055301. The next prime is 21055319. The reversal of 21055305 is 50355012.

It is not a de Polignac number, because 21055305 - 2² = 21055301 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21055301) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 41946 + ... + 42444.

It is an arithmetic number, because the mean of its divisors is an integer number (1102500).

Almost surely, 2^21055305 is an apocalyptic number.

It is an amenable number.

21055305 is a deficient number, since it is larger than the sum of its proper divisors (14224695).

21055305 is a wasteful number, since it uses less digits than its factorization.

21055305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 633.

The product of its (nonzero) digits is 750, while the sum is 21.

The square root of 21055305 is about 4588.6059974681. The cubic root of 21055305 is about 276.1343994663.

The spelling of 21055305 in words is "twenty-one million, fifty-five thousand, three hundred five".