820997971 has 2 divisors, whose sum is σ = 820997972. Its totient is φ = 820997970.

The previous prime is 820997959. The next prime is 820997987. The reversal of 820997971 is 179799028.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 820997971 - 2¹⁵ = 820965203 is a prime.

It is a super-2 number, since 2×820997971² = 1348075336772233682, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (820997951) 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, 410498985 + 410498986.

It is an arithmetic number, because the mean of its divisors is an integer number (410498986).

Almost surely, 2^820997971 is an apocalyptic number.

820997971 is a deficient number, since it is larger than the sum of its proper divisors (1).

820997971 is an equidigital number, since it uses as much as digits as its factorization.

820997971 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 571536, while the sum is 52.

The square root of 820997971 is about 28653.0621574728. The cubic root of 820997971 is about 936.3697201812.

The spelling of 820997971 in words is "eight hundred twenty million, nine hundred ninety-seven thousand, nine hundred seventy-one".