1685370221 has 2 divisors, whose sum is σ = 1685370222. Its totient is φ = 1685370220.

The previous prime is 1685370187. The next prime is 1685370233. The reversal of 1685370221 is 1220735861.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1682148196 + 3222025 = 41014^2 + 1795^2 .

It is an emirp because it is prime and its reverse (1220735861) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1685370221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1685379221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 842685110 + 842685111.

It is an arithmetic number, because the mean of its divisors is an integer number (842685111).

Almost surely, 2^1685370221 is an apocalyptic number.

It is an amenable number.

1685370221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1685370221 is an equidigital number, since it uses as much as digits as its factorization.

1685370221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 1685370221 is about 41053.2607840108. The cubic root of 1685370221 is about 1190.0497168693.

The spelling of 1685370221 in words is "one billion, six hundred eighty-five million, three hundred seventy thousand, two hundred twenty-one".