21779447 has 2 divisors, whose sum is σ = 21779448. Its totient is φ = 21779446.

The previous prime is 21779423. The next prime is 21779473. The reversal of 21779447 is 74497712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21779447 - 2⁶ = 21779383 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21779497) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10889723 + 10889724.

It is an arithmetic number, because the mean of its divisors is an integer number (10889724).

Almost surely, 2^21779447 is an apocalyptic number.

21779447 is a deficient number, since it is larger than the sum of its proper divisors (1).

21779447 is an equidigital number, since it uses as much as digits as its factorization.

21779447 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 98784, while the sum is 41.

The square root of 21779447 is about 4666.8455084779. The cubic root of 21779447 is about 279.2644255929.

The spelling of 21779447 in words is "twenty-one million, seven hundred seventy-nine thousand, four hundred forty-seven".