21428738 has 32 divisors (see below), whose sum is σ = 35717760. Its totient is φ = 9596160.

The previous prime is 21428731. The next prime is 21428747. The reversal of 21428738 is 83782412.

It is a junction number, because it is equal to n+sod(n) for n = 21428698 and 21428707.

It is not an unprimeable number, because it can be changed into a prime (21428731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 101453 + ... + 101663.

It is an arithmetic number, because the mean of its divisors is an integer number (1116180).

Almost surely, 2^21428738 is an apocalyptic number.

21428738 is a deficient number, since it is larger than the sum of its proper divisors (14289022).

21428738 is a wasteful number, since it uses less digits than its factorization.

21428738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 362.

The product of its digits is 21504, while the sum is 35.

The square root of 21428738 is about 4629.1184905984. The cubic root of 21428738 is about 277.7573318403.

The spelling of 21428738 in words is "twenty-one million, four hundred twenty-eight thousand, seven hundred thirty-eight".