21367901993 has 2 divisors, whose sum is σ = 21367901994. Its totient is φ = 21367901992.

The previous prime is 21367901983. The next prime is 21367902001. The reversal of 21367901993 is 39910976312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21009632809 + 358269184 = 144947^2 + 18928^2 .

It is a cyclic number.

It is not a de Polignac number, because 21367901993 - 2²² = 21363707689 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21367901983) 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, 10683950996 + 10683950997.

It is an arithmetic number, because the mean of its divisors is an integer number (10683950997).

Almost surely, 2^21367901993 is an apocalyptic number.

It is an amenable number.

21367901993 is a deficient number, since it is larger than the sum of its proper divisors (1).

21367901993 is an equidigital number, since it uses as much as digits as its factorization.

21367901993 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 551124, while the sum is 50.

The spelling of 21367901993 in words is "twenty-one billion, three hundred sixty-seven million, nine hundred one thousand, nine hundred ninety-three".