400069991 has 2 divisors, whose sum is σ = 400069992. Its totient is φ = 400069990.

The previous prime is 400069961. The next prime is 400069997. The reversal of 400069991 is 199960004.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 400069991 - 2¹⁰ = 400068967 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400069997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200034995 + 200034996.

It is an arithmetic number, because the mean of its divisors is an integer number (200034996).

Almost surely, 2^400069991 is an apocalyptic number.

400069991 is a deficient number, since it is larger than the sum of its proper divisors (1).

400069991 is an equidigital number, since it uses as much as digits as its factorization.

400069991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17496, while the sum is 38.

The square root of 400069991 is about 20001.7496984639. The cubic root of 400069991 is about 736.8492720632.

The spelling of 400069991 in words is "four hundred million, sixty-nine thousand, nine hundred ninety-one".