21158428 has 12 divisors (see below), whose sum is σ = 37065952. Its totient is φ = 10568160.

The previous prime is 21158377. The next prime is 21158471. The reversal of 21158428 is 82485112.

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21158428.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 2776 + ... + 7072.

Almost surely, 2^21158428 is an apocalyptic number.

It is an amenable number.

21158428 is a deficient number, since it is larger than the sum of its proper divisors (15907524).

21158428 is a wasteful number, since it uses less digits than its factorization.

21158428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5532 (or 5530 counting only the distinct ones).

The product of its digits is 5120, while the sum is 31.

The square root of 21158428 is about 4599.8291272611. The cubic root of 21158428 is about 276.5844751900.

The spelling of 21158428 in words is "twenty-one million, one hundred fifty-eight thousand, four hundred twenty-eight".