21002100709 has 2 divisors, whose sum is σ = 21002100710. Its totient is φ = 21002100708.

The previous prime is 21002100697. The next prime is 21002100727. The reversal of 21002100709 is 90700120012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18578507809 + 2423592900 = 136303^2 + 49230^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21002100709 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21002100709.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002100739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501050354 + 10501050355.

It is an arithmetic number, because the mean of its divisors is an integer number (10501050355).

Almost surely, 2^21002100709 is an apocalyptic number.

It is an amenable number.

21002100709 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002100709 is an equidigital number, since it uses as much as digits as its factorization.

21002100709 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 252, while the sum is 22.

The spelling of 21002100709 in words is "twenty-one billion, two million, one hundred thousand, seven hundred nine".