21478305 has 16 divisors (see below), whose sum is σ = 34499520. Its totient is φ = 11410368.

The previous prime is 21478291. The next prime is 21478307. The reversal of 21478305 is 50387412.

It is not a de Polignac number, because 21478305 - 2⁸ = 21478049 is a prime.

It is a super-2 number, since 2×21478305² = 922635171346050, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (21478307) 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, 1374 + ... + 6696.

It is an arithmetic number, because the mean of its divisors is an integer number (2156220).

Almost surely, 2^21478305 is an apocalyptic number.

It is an amenable number.

21478305 is a deficient number, since it is larger than the sum of its proper divisors (13021215).

21478305 is a wasteful number, since it uses less digits than its factorization.

21478305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5600.

The product of its (nonzero) digits is 6720, while the sum is 30.

The square root of 21478305 is about 4634.4692252727. The cubic root of 21478305 is about 277.9713278919.

The spelling of 21478305 in words is "twenty-one million, four hundred seventy-eight thousand, three hundred five".