4099981 has 2 divisors, whose sum is σ = 4099982. Its totient is φ = 4099980.

The previous prime is 4099961. The next prime is 4100011. The reversal of 4099981 is 1899904.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2223081 + 1876900 = 1491^2 + 1370^2 .

It is a cyclic number.

It is not a de Polignac number, because 4099981 - 2⁷ = 4099853 is a prime.

It is a super-2 number, since 2×4099981² = 33619688400722, which contains 22 as substring.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4099961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2049990 + 2049991.

It is an arithmetic number, because the mean of its divisors is an integer number (2049991).

Almost surely, 2^4099981 is an apocalyptic number.

It is an amenable number.

4099981 is a deficient number, since it is larger than the sum of its proper divisors (1).

4099981 is an equidigital number, since it uses as much as digits as its factorization.

4099981 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 40.

The square root of 4099981 is about 2024.8409814106. The cubic root of 4099981 is about 160.0518191530.

The spelling of 4099981 in words is "four million, ninety-nine thousand, nine hundred eighty-one".