40138991 has 2 divisors, whose sum is σ = 40138992. Its totient is φ = 40138990.

The previous prime is 40138957. The next prime is 40138999. The reversal of 40138991 is 19983104.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 40138991 - 2²² = 35944687 is a prime.

It is a super-2 number, since 2×40138991² = 3222277196996162, 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 (40138999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20069495 + 20069496.

It is an arithmetic number, because the mean of its divisors is an integer number (20069496).

Almost surely, 2^40138991 is an apocalyptic number.

40138991 is a deficient number, since it is larger than the sum of its proper divisors (1).

40138991 is an equidigital number, since it uses as much as digits as its factorization.

40138991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7776, while the sum is 35.

The square root of 40138991 is about 6335.5339948579. The cubic root of 40138991 is about 342.3908501891.

The spelling of 40138991 in words is "forty million, one hundred thirty-eight thousand, nine hundred ninety-one".