21730901779 has 2 divisors, whose sum is σ = 21730901780. Its totient is φ = 21730901778.

The previous prime is 21730901747. The next prime is 21730901783. The reversal of 21730901779 is 97710903712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21730901779 - 2⁵ = 21730901747 is a prime.

It is not a weakly prime, because it can be changed into another prime (21730901579) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10865450889 + 10865450890.

It is an arithmetic number, because the mean of its divisors is an integer number (10865450890).

Almost surely, 2^21730901779 is an apocalyptic number.

21730901779 is a deficient number, since it is larger than the sum of its proper divisors (1).

21730901779 is an equidigital number, since it uses as much as digits as its factorization.

21730901779 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 166698, while the sum is 46.

The spelling of 21730901779 in words is "twenty-one billion, seven hundred thirty million, nine hundred one thousand, seven hundred seventy-nine".