21628897 has 4 divisors (see below), whose sum is σ = 22767280. Its totient is φ = 20490516.

The previous prime is 21628891. The next prime is 21628907. The reversal of 21628897 is 79882612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21628897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21628891) by changing a digit.

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, 569163 + ... + 569200.

It is an arithmetic number, because the mean of its divisors is an integer number (5691820).

Almost surely, 2^21628897 is an apocalyptic number.

It is an amenable number.

21628897 is a deficient number, since it is larger than the sum of its proper divisors (1138383).

21628897 is a wasteful number, since it uses less digits than its factorization.

21628897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1138382.

The product of its digits is 96768, while the sum is 43.

The square root of 21628897 is about 4650.6877985950. The cubic root of 21628897 is about 278.6194672610.

The spelling of 21628897 in words is "twenty-one million, six hundred twenty-eight thousand, eight hundred ninety-seven".