201688381 has 2 divisors, whose sum is σ = 201688382. Its totient is φ = 201688380.

The previous prime is 201688379. The next prime is 201688441. The reversal of 201688381 is 183886102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 191822500 + 9865881 = 13850^2 + 3141^2 .

It is a cyclic number.

It is not a de Polignac number, because 201688381 - 2¹ = 201688379 is a prime.

It is a super-2 number, since 2×201688381² = 81356406060802322, which contains 22 as substring.

Together with 201688379, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 201688381.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (201688181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100844190 + 100844191.

It is an arithmetic number, because the mean of its divisors is an integer number (100844191).

Almost surely, 2^201688381 is an apocalyptic number.

It is an amenable number.

201688381 is a deficient number, since it is larger than the sum of its proper divisors (1).

201688381 is an equidigital number, since it uses as much as digits as its factorization.

201688381 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18432, while the sum is 37.

The square root of 201688381 is about 14201.7034541635. The cubic root of 201688381 is about 586.4445571844. Note that the first 3 decimals are identical.

The spelling of 201688381 in words is "two hundred one million, six hundred eighty-eight thousand, three hundred eighty-one".