40199981 has 2 divisors, whose sum is σ = 40199982. Its totient is φ = 40199980.

The previous prime is 40199977. The next prime is 40199983. The reversal of 40199981 is 18999104.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 30151081 + 10048900 = 5491^2 + 3170^2 .

It is a cyclic number.

It is not a de Polignac number, because 40199981 - 2² = 40199977 is a prime.

It is a super-2 number, since 2×40199981² = 3232076944800722, which contains 22 as substring.

Together with 40199983, 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 (40199983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20099990 + 20099991.

It is an arithmetic number, because the mean of its divisors is an integer number (20099991).

Almost surely, 2^40199981 is an apocalyptic number.

It is an amenable number.

40199981 is a deficient number, since it is larger than the sum of its proper divisors (1).

40199981 is an equidigital number, since it uses as much as digits as its factorization.

40199981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 41.

The square root of 40199981 is about 6340.3454953181. The cubic root of 40199981 is about 342.5641799915.

The spelling of 40199981 in words is "forty million, one hundred ninety-nine thousand, nine hundred eighty-one".