21343561991 has 2 divisors, whose sum is σ = 21343561992. Its totient is φ = 21343561990.

The previous prime is 21343561963. The next prime is 21343561997. The reversal of 21343561991 is 19916534312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21343561991 - 2¹⁴ = 21343545607 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21343561997) 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, 10671780995 + 10671780996.

It is an arithmetic number, because the mean of its divisors is an integer number (10671780996).

Almost surely, 2^21343561991 is an apocalyptic number.

21343561991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21343561991 is an equidigital number, since it uses as much as digits as its factorization.

21343561991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 174960, while the sum is 44.

The spelling of 21343561991 in words is "twenty-one billion, three hundred forty-three million, five hundred sixty-one thousand, nine hundred ninety-one".