21046305 has 32 divisors (see below), whose sum is σ = 38697984. Its totient is φ = 9567936.

The previous prime is 21046301. The next prime is 21046309. The reversal of 21046305 is 50364012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21046301) and next prime (21046309).

It is not a de Polignac number, because 21046305 - 2² = 21046301 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21046301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 23394 + ... + 24276.

It is an arithmetic number, because the mean of its divisors is an integer number (1209312).

Almost surely, 2^21046305 is an apocalyptic number.

21046305 is the 2649-th octagonal number.

It is an amenable number.

21046305 is a deficient number, since it is larger than the sum of its proper divisors (17651679).

21046305 is a wasteful number, since it uses less digits than its factorization.

21046305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1125.

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 21046305 is about 4587.6252026511. The cubic root of 21046305 is about 276.0950497034.

The spelling of 21046305 in words is "twenty-one million, forty-six thousand, three hundred five".