21305478 has 16 divisors (see below), whose sum is σ = 42771456. Its totient is φ = 7075080.

The previous prime is 21305461. The next prime is 21305483. The reversal of 21305478 is 87450312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4926 + ... + 8177.

It is an arithmetic number, because the mean of its divisors is an integer number (2673216).

Almost surely, 2^21305478 is an apocalyptic number.

21305478 is an abundant number, since it is smaller than the sum of its proper divisors (21465978).

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

21305478 is a wasteful number, since it uses less digits than its factorization.

21305478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13379.

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

The square root of 21305478 is about 4615.7857402613. The cubic root of 21305478 is about 277.2237458549.

The spelling of 21305478 in words is "twenty-one million, three hundred five thousand, four hundred seventy-eight".