21002100997 has 2 divisors, whose sum is σ = 21002100998. Its totient is φ = 21002100996.

The previous prime is 21002100989. The next prime is 21002101033. The reversal of 21002100997 is 79900120012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20861180356 + 140920641 = 144434^2 + 11871^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002100997 - 2³ = 21002100989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002100907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501050498 + 10501050499.

It is an arithmetic number, because the mean of its divisors is an integer number (10501050499).

Almost surely, 2^21002100997 is an apocalyptic number.

It is an amenable number.

21002100997 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002100997 is an equidigital number, since it uses as much as digits as its factorization.

21002100997 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2268, while the sum is 31.

The spelling of 21002100997 in words is "twenty-one billion, two million, one hundred thousand, nine hundred ninety-seven".