820909181 has 2 divisors, whose sum is σ = 820909182. Its totient is φ = 820909180.

The previous prime is 820909153. The next prime is 820909189. The reversal of 820909181 is 181909028.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 592143556 + 228765625 = 24334^2 + 15125^2 .

It is a cyclic number.

It is not a de Polignac number, because 820909181 - 2¹⁴ = 820892797 is a prime.

It is a super-2 number, since 2×820909181² = 1347783766900181522, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (820909189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410454590 + 410454591.

It is an arithmetic number, because the mean of its divisors is an integer number (410454591).

Almost surely, 2^820909181 is an apocalyptic number.

It is an amenable number.

820909181 is a deficient number, since it is larger than the sum of its proper divisors (1).

820909181 is an equidigital number, since it uses as much as digits as its factorization.

820909181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10368, while the sum is 38.

The square root of 820909181 is about 28651.5127174814. The cubic root of 820909181 is about 936.3359631896.

The spelling of 820909181 in words is "eight hundred twenty million, nine hundred nine thousand, one hundred eighty-one".