999742621909 has 2 divisors, whose sum is σ = 999742621910. Its totient is φ = 999742621908.

The previous prime is 999742621897. The next prime is 999742621919. The reversal of 999742621909 is 909126247999.

999742621909 = T₈₁₆₃₉₀ + T₈₁₆₃₉₁ + T₈₁₆₃₉₂.

999742621909 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 992320799409 + 7421822500 = 996153^2 + 86150^2 .

It is a cyclic number.

It is not a de Polignac number, because 999742621909 - 2⁷ = 999742621781 is a prime.

It is a super-2 number, since 2×999742621909² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999742621919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499871310954 + 499871310955.

It is an arithmetic number, because the mean of its divisors is an integer number (499871310955).

Almost surely, 2^999742621909 is an apocalyptic number.

999742621909 is the 816392-nd centered triangular number.

It is an amenable number.

999742621909 is a deficient number, since it is larger than the sum of its proper divisors (1).

999742621909 is an equidigital number, since it uses as much as digits as its factorization.

999742621909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 39680928, while the sum is 67.

The spelling of 999742621909 in words is "nine hundred ninety-nine billion, seven hundred forty-two million, six hundred twenty-one thousand, nine hundred nine".