210021971 has 2 divisors, whose sum is σ = 210021972. Its totient is φ = 210021970.

The previous prime is 210021937. The next prime is 210021983. The reversal of 210021971 is 179120012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-210021971 is a prime.

It is not a weakly prime, because it can be changed into another prime (210021271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105010985 + 105010986.

It is an arithmetic number, because the mean of its divisors is an integer number (105010986).

Almost surely, 2^210021971 is an apocalyptic number.

210021971 is a deficient number, since it is larger than the sum of its proper divisors (1).

210021971 is an equidigital number, since it uses as much as digits as its factorization.

210021971 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 252, while the sum is 23.

The square root of 210021971 is about 14492.1347978826. The cubic root of 210021971 is about 594.4129237454.

Adding to 210021971 its reverse (179120012), we get a palindrome (389141983).

The spelling of 210021971 in words is "two hundred ten million, twenty-one thousand, nine hundred seventy-one".