83820721 has 2 divisors, whose sum is σ = 83820722. Its totient is φ = 83820720.

The previous prime is 83820691. The next prime is 83820733. The reversal of 83820721 is 12702838.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52056225 + 31764496 = 7215^2 + 5636^2 .

It is a cyclic number.

It is not a de Polignac number, because 83820721 - 2²³ = 75432113 is a prime.

It is not a weakly prime, because it can be changed into another prime (83820221) 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, 41910360 + 41910361.

It is an arithmetic number, because the mean of its divisors is an integer number (41910361).

Almost surely, 2^83820721 is an apocalyptic number.

It is an amenable number.

83820721 is a deficient number, since it is larger than the sum of its proper divisors (1).

83820721 is an equidigital number, since it uses as much as digits as its factorization.

83820721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5376, while the sum is 31.

The square root of 83820721 is about 9155.3656944985. The cubic root of 83820721 is about 437.6401223006.

The spelling of 83820721 in words is "eighty-three million, eight hundred twenty thousand, seven hundred twenty-one".