416665721 has 2 divisors, whose sum is σ = 416665722. Its totient is φ = 416665720.

The previous prime is 416665679. The next prime is 416665747. The reversal of 416665721 is 127566614.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 320410000 + 96255721 = 17900^2 + 9811^2 .

It is a cyclic number.

It is not a de Polignac number, because 416665721 - 2¹⁸ = 416403577 is a prime.

It is a super-2 number, since 2×416665721² = 347220646112899682, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (416655721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 208332860 + 208332861.

It is an arithmetic number, because the mean of its divisors is an integer number (208332861).

Almost surely, 2^416665721 is an apocalyptic number.

It is an amenable number.

416665721 is a deficient number, since it is larger than the sum of its proper divisors (1).

416665721 is an equidigital number, since it uses as much as digits as its factorization.

416665721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 60480, while the sum is 38.

The square root of 416665721 is about 20412.3913591720. The cubic root of 416665721 is about 746.9002260371.

The spelling of 416665721 in words is "four hundred sixteen million, six hundred sixty-five thousand, seven hundred twenty-one".