404999981 has 2 divisors, whose sum is σ = 404999982. Its totient is φ = 404999980.

The previous prime is 404999971. The next prime is 404999983. The reversal of 404999981 is 189999404.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 290702500 + 114297481 = 17050^2 + 10691^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-404999981 is a prime.

It is a super-2 number, since 2×404999981² = 328049969220000722, which contains 22 as substring.

Together with 404999983, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (404999983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 202499990 + 202499991.

It is an arithmetic number, because the mean of its divisors is an integer number (202499991).

Almost surely, 2^404999981 is an apocalyptic number.

It is an amenable number.

404999981 is a deficient number, since it is larger than the sum of its proper divisors (1).

404999981 is an equidigital number, since it uses as much as digits as its factorization.

404999981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 839808, while the sum is 53.

The square root of 404999981 is about 20124.6113254393. The cubic root of 404999981 is about 739.8636107293.

The spelling of 404999981 in words is "four hundred four million, nine hundred ninety-nine thousand, nine hundred eighty-one".