891768221 has 4 divisors (see below), whose sum is σ = 898575744. Its totient is φ = 884960700.

The previous prime is 891768193. The next prime is 891768223. The reversal of 891768221 is 122867198.

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 not a de Polignac number, because 891768221 - 2²⁶ = 824659357 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (891768223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3403565 + ... + 3403826.

It is an arithmetic number, because the mean of its divisors is an integer number (224643936).

Almost surely, 2^891768221 is an apocalyptic number.

It is an amenable number.

891768221 is a deficient number, since it is larger than the sum of its proper divisors (6807523).

891768221 is a wasteful number, since it uses less digits than its factorization.

891768221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6807522.

The product of its digits is 96768, while the sum is 44.

The square root of 891768221 is about 29862.4885265780. The cubic root of 891768221 is about 962.5367734531.

The spelling of 891768221 in words is "eight hundred ninety-one million, seven hundred sixty-eight thousand, two hundred twenty-one".