21002120291 has 2 divisors, whose sum is σ = 21002120292. Its totient is φ = 21002120290.

The previous prime is 21002120287. The next prime is 21002120311. The reversal of 21002120291 is 19202120012.

It is a happy number.

It is an a-pointer prime, because the next prime (21002120311) can be obtained adding 21002120291 to its sum of digits (20).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21002120291 - 2² = 21002120287 is a prime.

It is not a weakly prime, because it can be changed into another prime (21002120261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501060145 + 10501060146.

It is an arithmetic number, because the mean of its divisors is an integer number (10501060146).

Almost surely, 2^21002120291 is an apocalyptic number.

21002120291 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002120291 is an equidigital number, since it uses as much as digits as its factorization.

21002120291 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144, while the sum is 20.

The spelling of 21002120291 in words is "twenty-one billion, two million, one hundred twenty thousand, two hundred ninety-one".