21135428 has 12 divisors (see below), whose sum is σ = 38180352. Its totient is φ = 10226760.

The previous prime is 21135421. The next prime is 21135431. The reversal of 21135428 is 82453112.

It is a junction number, because it is equal to n+sod(n) for n = 21135397 and 21135406.

It is not an unprimeable number, because it can be changed into a prime (21135421) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 85100 + ... + 85347.

It is an arithmetic number, because the mean of its divisors is an integer number (3181696).

Almost surely, 2^21135428 is an apocalyptic number.

It is an amenable number.

21135428 is a deficient number, since it is larger than the sum of its proper divisors (17044924).

21135428 is a wasteful number, since it uses less digits than its factorization.

21135428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170482 (or 170480 counting only the distinct ones).

The product of its digits is 1920, while the sum is 26.

The square root of 21135428 is about 4597.3283545990. The cubic root of 21135428 is about 276.4842196423.

The spelling of 21135428 in words is "twenty-one million, one hundred thirty-five thousand, four hundred twenty-eight".