21011011993 has 8 divisors (see below), whose sum is σ = 21583169928. Its totient is φ = 20439080064.

The previous prime is 21011011979. The next prime is 21011011997. The reversal of 21011011993 is 39911011012.

It can be written as a sum of positive squares in 4 ways, for example, as 11485837584 + 9525174409 = 107172^2 + 97597^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21011011993 - 2⁹ = 21011011481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21011011997) 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 in 7 ways as a sum of consecutive naturals, for example, 141255 + ... + 248947.

It is an arithmetic number, because the mean of its divisors is an integer number (2697896241).

Almost surely, 2^21011011993 is an apocalyptic number.

It is an amenable number.

21011011993 is a deficient number, since it is larger than the sum of its proper divisors (572157935).

21011011993 is a wasteful number, since it uses less digits than its factorization.

21011011993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113003.

The product of its (nonzero) digits is 486, while the sum is 28.

The spelling of 21011011993 in words is "twenty-one billion, eleven million, eleven thousand, nine hundred ninety-three".