201720031 has 4 divisors (see below), whose sum is σ = 202034392. Its totient is φ = 201405672.

The previous prime is 201719989. The next prime is 201720047. The reversal of 201720031 is 130027102.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 201720031 - 2²¹ = 199622879 is a prime.

It is a super-2 number, since 2×201720031² = 81381941813281922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 201719987 and 201720014.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (201720091) 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 in 3 ways as a sum of consecutive naturals, for example, 156216 + ... + 157501.

It is an arithmetic number, because the mean of its divisors is an integer number (50508598).

Almost surely, 2^201720031 is an apocalyptic number.

201720031 is a deficient number, since it is larger than the sum of its proper divisors (314361).

201720031 is an equidigital number, since it uses as much as digits as its factorization.

201720031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 314360.

The product of its (nonzero) digits is 84, while the sum is 16.

The square root of 201720031 is about 14202.8177133976. The cubic root of 201720031 is about 586.4752315666.

Adding to 201720031 its reverse (130027102), we get a palindrome (331747133).

The spelling of 201720031 in words is "two hundred one million, seven hundred twenty thousand, thirty-one".