21157128 has 48 divisors (see below), whose sum is σ = 59155200. Its totient is φ = 6824160.

The previous prime is 21157121. The next prime is 21157139. The reversal of 21157128 is 82175112.

It is not an unprimeable number, because it can be changed into a prime (21157121) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2508 + ... + 6971.

It is an arithmetic number, because the mean of its divisors is an integer number (1232400).

Almost surely, 2^21157128 is an apocalyptic number.

It is an amenable number.

21157128 is an abundant number, since it is smaller than the sum of its proper divisors (37998072).

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

21157128 is a wasteful number, since it uses less digits than its factorization.

21157128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9522 (or 9515 counting only the distinct ones).

The product of its digits is 1120, while the sum is 27.

The square root of 21157128 is about 4599.6878154936. The cubic root of 21157128 is about 276.5788105099.

The spelling of 21157128 in words is "twenty-one million, one hundred fifty-seven thousand, one hundred twenty-eight".