21002003001971 has 2 divisors, whose sum is σ = 21002003001972. Its totient is φ = 21002003001970.

The previous prime is 21002003001949. The next prime is 21002003002021. The reversal of 21002003001971 is 17910030020012.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21002003001971 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21002003001971.

It is not a weakly prime, because it can be changed into another prime (21002003001901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501001500985 + 10501001500986.

It is an arithmetic number, because the mean of its divisors is an integer number (10501001500986).

Almost surely, 2^{21002003001971} is an apocalyptic number.

21002003001971 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002003001971 is an equidigital number, since it uses as much as digits as its factorization.

21002003001971 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 756, while the sum is 26.

Adding to 21002003001971 its reverse (17910030020012), we get a palindrome (38912033021983).

The spelling of 21002003001971 in words is "twenty-one trillion, two billion, three million, one thousand, nine hundred seventy-one".