21822779 has 4 divisors (see below), whose sum is σ = 23806680. Its totient is φ = 19838880.

The previous prime is 21822763. The next prime is 21822793. The reversal of 21822779 is 97722812.

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 21822779 - 2⁴ = 21822763 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21822709) 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, 991934 + ... + 991955.

It is an arithmetic number, because the mean of its divisors is an integer number (5951670).

Almost surely, 2^21822779 is an apocalyptic number.

21822779 is a deficient number, since it is larger than the sum of its proper divisors (1983901).

21822779 is a wasteful number, since it uses less digits than its factorization.

21822779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1983900.

The product of its digits is 28224, while the sum is 38.

The square root of 21822779 is about 4671.4857379639. The cubic root of 21822779 is about 279.4495094103.

The spelling of 21822779 in words is "twenty-one million, eight hundred twenty-two thousand, seven hundred seventy-nine".