21922778 has 4 divisors (see below), whose sum is σ = 32884170. Its totient is φ = 10961388.

The previous prime is 21922763. The next prime is 21922781. The reversal of 21922778 is 87722912.

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

It can be written as a sum of positive squares in only one way, i.e., 21836929 + 85849 = 4673^2 + 293^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5480693 + ... + 5480696.

Almost surely, 2^21922778 is an apocalyptic number.

21922778 is a deficient number, since it is larger than the sum of its proper divisors (10961392).

21922778 is a wasteful number, since it uses less digits than its factorization.

21922778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10961391.

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

The square root of 21922778 is about 4682.1766305854. The cubic root of 21922778 is about 279.8757016320.

The spelling of 21922778 in words is "twenty-one million, nine hundred twenty-two thousand, seven hundred seventy-eight".