21489231779 has 2 divisors, whose sum is σ = 21489231780. Its totient is φ = 21489231778.

The previous prime is 21489231767. The next prime is 21489231787. The reversal of 21489231779 is 97713298412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21489231779 - 2⁴ = 21489231763 is a prime.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21489231779.

It is not a weakly prime, because it can be changed into another prime (21489231079) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10744615889 + 10744615890.

It is an arithmetic number, because the mean of its divisors is an integer number (10744615890).

Almost surely, 2^21489231779 is an apocalyptic number.

21489231779 is a deficient number, since it is larger than the sum of its proper divisors (1).

21489231779 is an equidigital number, since it uses as much as digits as its factorization.

21489231779 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1524096, while the sum is 53.

The spelling of 21489231779 in words is "twenty-one billion, four hundred eighty-nine million, two hundred thirty-one thousand, seven hundred seventy-nine".