21128577 has 8 divisors (see below), whose sum is σ = 29080320. Its totient is φ = 13631280.

The previous prime is 21128573. The next prime is 21128587. The reversal of 21128577 is 77582112.

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

It is not a de Polignac number, because 21128577 - 2² = 21128573 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21128573) 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, 113502 + ... + 113687.

It is an arithmetic number, because the mean of its divisors is an integer number (3635040).

Almost surely, 2^21128577 is an apocalyptic number.

It is an amenable number.

21128577 is a deficient number, since it is larger than the sum of its proper divisors (7951743).

21128577 is a wasteful number, since it uses less digits than its factorization.

21128577 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 227223.

The product of its digits is 7840, while the sum is 33.

The square root of 21128577 is about 4596.5831875427. The cubic root of 21128577 is about 276.4543425075.

The spelling of 21128577 in words is "twenty-one million, one hundred twenty-eight thousand, five hundred seventy-seven".