21021100993 has 4 divisors (see below), whose sum is σ = 21365709268. Its totient is φ = 20676492720.

The previous prime is 21021100987. The next prime is 21021101051. The reversal of 21021100993 is 39900112012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11894737969 + 9126363024 = 109063^2 + 95532^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021100993 - 2³³ = 12431166401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21021100943) 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 3 ways as a sum of consecutive naturals, for example, 172304046 + ... + 172304167.

It is an arithmetic number, because the mean of its divisors is an integer number (5341427317).

Almost surely, 2^21021100993 is an apocalyptic number.

It is an amenable number.

21021100993 is a deficient number, since it is larger than the sum of its proper divisors (344608275).

21021100993 is an equidigital number, since it uses as much as digits as its factorization.

21021100993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 344608274.

The product of its (nonzero) digits is 972, while the sum is 28.

The spelling of 21021100993 in words is "twenty-one billion, twenty-one million, one hundred thousand, nine hundred ninety-three".