405887981 has 2 divisors, whose sum is σ = 405887982. Its totient is φ = 405887980.

The previous prime is 405887959. The next prime is 405888001. The reversal of 405887981 is 189788504.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 405015625 + 872356 = 20125^2 + 934^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-405887981 is a prime.

It is a super-2 number, since 2×405887981² = 329490106240512722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (405887381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 202943990 + 202943991.

It is an arithmetic number, because the mean of its divisors is an integer number (202943991).

Almost surely, 2^405887981 is an apocalyptic number.

It is an amenable number.

405887981 is a deficient number, since it is larger than the sum of its proper divisors (1).

405887981 is an equidigital number, since it uses as much as digits as its factorization.

405887981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 645120, while the sum is 50.

The square root of 405887981 is about 20146.6617830349. The cubic root of 405887981 is about 740.4039558521.

The spelling of 405887981 in words is "four hundred five million, eight hundred eighty-seven thousand, nine hundred eighty-one".