163909721 has 2 divisors, whose sum is σ = 163909722. Its totient is φ = 163909720.

The previous prime is 163909709. The next prime is 163909783. The reversal of 163909721 is 127909361.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 162919696 + 990025 = 12764^2 + 995^2 .

It is a cyclic number.

It is not a de Polignac number, because 163909721 - 2¹⁰ = 163908697 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (163909321) 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, 81954860 + 81954861.

It is an arithmetic number, because the mean of its divisors is an integer number (81954861).

Almost surely, 2^163909721 is an apocalyptic number.

It is an amenable number.

163909721 is a deficient number, since it is larger than the sum of its proper divisors (1).

163909721 is an equidigital number, since it uses as much as digits as its factorization.

163909721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20412, while the sum is 38.

The square root of 163909721 is about 12802.7231868849. The cubic root of 163909721 is about 547.2699099194.

The spelling of 163909721 in words is "one hundred sixty-three million, nine hundred nine thousand, seven hundred twenty-one".