188721317 has 2 divisors, whose sum is σ = 188721318. Its totient is φ = 188721316.

The previous prime is 188721229. The next prime is 188721341. The reversal of 188721317 is 713127881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 104980516 + 83740801 = 10246^2 + 9151^2 .

It is a cyclic number.

It is not a de Polignac number, because 188721317 - 2⁸ = 188721061 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (188721347) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94360658 + 94360659.

It is an arithmetic number, because the mean of its divisors is an integer number (94360659).

Almost surely, 2^188721317 is an apocalyptic number.

It is an amenable number.

188721317 is a deficient number, since it is larger than the sum of its proper divisors (1).

188721317 is an equidigital number, since it uses as much as digits as its factorization.

188721317 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18816, while the sum is 38.

The square root of 188721317 is about 13737.5877431229. The cubic root of 188721317 is about 573.5971518490.

The spelling of 188721317 in words is "one hundred eighty-eight million, seven hundred twenty-one thousand, three hundred seventeen".