164721409 has 2 divisors, whose sum is σ = 164721410. Its totient is φ = 164721408.

The previous prime is 164721407. The next prime is 164721463. The reversal of 164721409 is 904127461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 141681409 + 23040000 = 11903^2 + 4800^2 .

It is a cyclic number.

It is not a de Polignac number, because 164721409 - 2¹ = 164721407 is a prime.

Together with 164721407, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (164721407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82360704 + 82360705.

It is an arithmetic number, because the mean of its divisors is an integer number (82360705).

Almost surely, 2^164721409 is an apocalyptic number.

It is an amenable number.

164721409 is a deficient number, since it is larger than the sum of its proper divisors (1).

164721409 is an equidigital number, since it uses as much as digits as its factorization.

164721409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 164721409 is about 12834.3838574355. The cubic root of 164721409 is about 548.1717908930.

The spelling of 164721409 in words is "one hundred sixty-four million, seven hundred twenty-one thousand, four hundred nine".