21307730501 has 2 divisors, whose sum is σ = 21307730502. Its totient is φ = 21307730500.

The previous prime is 21307730473. The next prime is 21307730513. The reversal of 21307730501 is 10503770312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20916679876 + 391050625 = 144626^2 + 19775^2 .

It is a cyclic number.

It is not a de Polignac number, because 21307730501 - 2¹⁴ = 21307714117 is a prime.

It is a super-2 number, since 2×21307730501² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21307730401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10653865250 + 10653865251.

It is an arithmetic number, because the mean of its divisors is an integer number (10653865251).

Almost surely, 2^21307730501 is an apocalyptic number.

It is an amenable number.

21307730501 is a deficient number, since it is larger than the sum of its proper divisors (1).

21307730501 is an equidigital number, since it uses as much as digits as its factorization.

21307730501 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4410, while the sum is 29.

The spelling of 21307730501 in words is "twenty-one billion, three hundred seven million, seven hundred thirty thousand, five hundred one".