21779223 has 4 divisors (see below), whose sum is σ = 29038968. Its totient is φ = 14519480.

The previous prime is 21779213. The next prime is 21779231. The reversal of 21779223 is 32297712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21779223 - 2¹³ = 21771031 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21779213) 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, 3629868 + ... + 3629873.

It is an arithmetic number, because the mean of its divisors is an integer number (7259742).

Almost surely, 2^21779223 is an apocalyptic number.

21779223 is a deficient number, since it is larger than the sum of its proper divisors (7259745).

21779223 is an equidigital number, since it uses as much as digits as its factorization.

21779223 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7259744.

The product of its digits is 10584, while the sum is 33.

The square root of 21779223 is about 4666.8215093359. The cubic root of 21779223 is about 279.2634681849.

The spelling of 21779223 in words is "twenty-one million, seven hundred seventy-nine thousand, two hundred twenty-three".