2021308120721 has 2 divisors, whose sum is σ = 2021308120722. Its totient is φ = 2021308120720.

The previous prime is 2021308120649. The next prime is 2021308120729. The reversal of 2021308120721 is 1270218031202.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2014313140225 + 6994980496 = 1419265^2 + 83636^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2021308120721 is a prime.

It is not a weakly prime, because it can be changed into another prime (2021308120729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1010654060360 + 1010654060361.

It is an arithmetic number, because the mean of its divisors is an integer number (1010654060361).

Almost surely, 2^{2021308120721} is an apocalyptic number.

It is an amenable number.

2021308120721 is a deficient number, since it is larger than the sum of its proper divisors (1).

2021308120721 is an equidigital number, since it uses as much as digits as its factorization.

2021308120721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2688, while the sum is 29.

The spelling of 2021308120721 in words is "two trillion, twenty-one billion, three hundred eight million, one hundred twenty thousand, seven hundred twenty-one".