21575428 has 12 divisors (see below), whose sum is σ = 43150912. Its totient is φ = 9246600.

The previous prime is 21575423. The next prime is 21575443. The reversal of 21575428 is 82457512.

It is a happy number.

21575428 is an admirable number.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21575393 and 21575402.

It is not an unprimeable number, because it can be changed into a prime (21575423) 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, 385248 + ... + 385303.

Almost surely, 2^21575428 is an apocalyptic number.

21575428 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21575428 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21575428 is a wasteful number, since it uses less digits than its factorization.

21575428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 770562 (or 770560 counting only the distinct ones).

The product of its digits is 22400, while the sum is 34.

The square root of 21575428 is about 4644.9357369075. The cubic root of 21575428 is about 278.3896852049.

The spelling of 21575428 in words is "twenty-one million, five hundred seventy-five thousand, four hundred twenty-eight".