201720491 has 16 divisors (see below), whose sum is σ = 243000000. Its totient is φ = 163782528.

The previous prime is 201720479. The next prime is 201720539. The reversal of 201720491 is 194027102.

It is a de Polignac number, because none of the positive numbers 2^k-201720491 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 201720491.

It is not an unprimeable number, because it can be changed into a prime (201720401) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1385 + ... + 20133.

It is an arithmetic number, because the mean of its divisors is an integer number (15187500).

Almost surely, 2^201720491 is an apocalyptic number.

201720491 is a deficient number, since it is larger than the sum of its proper divisors (41279509).

201720491 is a wasteful number, since it uses less digits than its factorization.

201720491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18838.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 201720491 is about 14202.8339073581. The cubic root of 201720491 is about 586.4756773633.

Adding to 201720491 its reverse (194027102), we get a palindrome (395747593).

The spelling of 201720491 in words is "two hundred one million, seven hundred twenty thousand, four hundred ninety-one".