21731225779 has 2 divisors, whose sum is σ = 21731225780. Its totient is φ = 21731225778.

The previous prime is 21731225759. The next prime is 21731225821. The reversal of 21731225779 is 97752213712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21731225779 - 2⁹ = 21731225267 is a prime.

It is not a weakly prime, because it can be changed into another prime (21731225759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10865612889 + 10865612890.

It is an arithmetic number, because the mean of its divisors is an integer number (10865612890).

Almost surely, 2^21731225779 is an apocalyptic number.

21731225779 is a deficient number, since it is larger than the sum of its proper divisors (1).

21731225779 is an equidigital number, since it uses as much as digits as its factorization.

21731225779 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 370440, while the sum is 46.

The spelling of 21731225779 in words is "twenty-one billion, seven hundred thirty-one million, two hundred twenty-five thousand, seven hundred seventy-nine".