2001409981 has 2 divisors, whose sum is σ = 2001409982. Its totient is φ = 2001409980.

The previous prime is 2001409979. The next prime is 2001410027. The reversal of 2001409981 is 1899041002.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1510565956 + 490844025 = 38866^2 + 22155^2 .

It is a cyclic number.

It is not a de Polignac number, because 2001409981 - 2¹ = 2001409979 is a prime.

It is a super-2 number, since 2×2001409981² = 8011283824092840722, which contains 22 as substring.

Together with 2001409979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2001409901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1000704990 + 1000704991.

It is an arithmetic number, because the mean of its divisors is an integer number (1000704991).

Almost surely, 2^2001409981 is an apocalyptic number.

It is an amenable number.

2001409981 is a deficient number, since it is larger than the sum of its proper divisors (1).

2001409981 is an equidigital number, since it uses as much as digits as its factorization.

2001409981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 2001409981 is about 44737.1208394103. The cubic root of 2001409981 is about 1260.2170578018.

The spelling of 2001409981 in words is "two billion, one million, four hundred nine thousand, nine hundred eighty-one".