21128497 has 8 divisors (see below), whose sum is σ = 22838144. Its totient is φ = 19430928.

The previous prime is 21128477. The next prime is 21128507. The reversal of 21128497 is 79482112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21128497 - 2¹¹ = 21126449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21128477) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 808 + ... + 6550.

It is an arithmetic number, because the mean of its divisors is an integer number (2854768).

Almost surely, 2^21128497 is an apocalyptic number.

It is an amenable number.

21128497 is a deficient number, since it is larger than the sum of its proper divisors (1709647).

21128497 is a wasteful number, since it uses less digits than its factorization.

21128497 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6039.

The product of its digits is 8064, while the sum is 34.

The square root of 21128497 is about 4596.5744854185. The cubic root of 21128497 is about 276.4539935903.

It can be divided in two parts, 2112 and 8497, that added together give a square (10609 = 103²).

The spelling of 21128497 in words is "twenty-one million, one hundred twenty-eight thousand, four hundred ninety-seven".