2151706021 has 2 divisors, whose sum is σ = 2151706022. Its totient is φ = 2151706020.

The previous prime is 2151706019. The next prime is 2151706033. The reversal of 2151706021 is 1206071512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1812630625 + 339075396 = 42575^2 + 18414^2 .

It is a cyclic number.

It is not a de Polignac number, because 2151706021 - 2¹ = 2151706019 is a prime.

Together with 2151706019, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2151706321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1075853010 + 1075853011.

It is an arithmetic number, because the mean of its divisors is an integer number (1075853011).

Almost surely, 2^2151706021 is an apocalyptic number.

It is an amenable number.

2151706021 is a deficient number, since it is larger than the sum of its proper divisors (1).

2151706021 is an equidigital number, since it uses as much as digits as its factorization.

2151706021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 840, while the sum is 25.

The square root of 2151706021 is about 46386.4853270864. The cubic root of 2151706021 is about 1291.0041699507.

Adding to 2151706021 its reverse (1206071512), we get a palindrome (3357777533).

The spelling of 2151706021 in words is "two billion, one hundred fifty-one million, seven hundred six thousand, twenty-one".