22778221 has 4 divisors (see below), whose sum is σ = 23262912. Its totient is φ = 22293532.

The previous prime is 22778213. The next prime is 22778233. The reversal of 22778221 is 12287722.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12287722 = 2 ⋅6143861.

It is a cyclic number.

It is not a de Polignac number, because 22778221 - 2³ = 22778213 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 (22778281) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 242275 + ... + 242368.

It is an arithmetic number, because the mean of its divisors is an integer number (5815728).

Almost surely, 2^22778221 is an apocalyptic number.

It is an amenable number.

22778221 is a deficient number, since it is larger than the sum of its proper divisors (484691).

22778221 is an equidigital number, since it uses as much as digits as its factorization.

22778221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 484690.

The product of its digits is 6272, while the sum is 31.

The square root of 22778221 is about 4772.6534548404. The cubic root of 22778221 is about 283.4696717160.

The spelling of 22778221 in words is "twenty-two million, seven hundred seventy-eight thousand, two hundred twenty-one".