21478905 has 96 divisors (see below), whose sum is σ = 47278080. Its totient is φ = 9192960.

The previous prime is 21478903. The next prime is 21478909. The reversal of 21478905 is 50987412.

It is not a de Polignac number, because 21478905 - 2¹ = 21478903 is a prime.

It is a super-2 number, since 2×21478905² = 922686719998050, which contains 22 as substring.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21478905.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21478901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 112360 + ... + 112550.

It is an arithmetic number, because the mean of its divisors is an integer number (492480).

Almost surely, 2^21478905 is an apocalyptic number.

It is an amenable number.

21478905 is an abundant number, since it is smaller than the sum of its proper divisors (25799175).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21478905 is a wasteful number, since it uses less digits than its factorization.

21478905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 236 (or 223 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The square root of 21478905 is about 4634.5339571525. The cubic root of 21478905 is about 277.9739162595.

The spelling of 21478905 in words is "twenty-one million, four hundred seventy-eight thousand, nine hundred five".