21420478 has 4 divisors (see below), whose sum is σ = 32130720. Its totient is φ = 10710238.

The previous prime is 21420449. The next prime is 21420479. The reversal of 21420478 is 87402412.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5355118 + ... + 5355121.

It is an arithmetic number, because the mean of its divisors is an integer number (8032680).

Almost surely, 2^21420478 is an apocalyptic number.

21420478 is a deficient number, since it is larger than the sum of its proper divisors (10710242).

21420478 is a wasteful number, since it uses less digits than its factorization.

21420478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10710241.

The product of its (nonzero) digits is 3584, while the sum is 28.

The square root of 21420478 is about 4628.2262261043. The cubic root of 21420478 is about 277.7216388002.

The spelling of 21420478 in words is "twenty-one million, four hundred twenty thousand, four hundred seventy-eight".