21011099 has 4 divisors (see below), whose sum is σ = 22247064. Its totient is φ = 19775136.

The previous prime is 21011083. The next prime is 21011141. The reversal of 21011099 is 99011012.

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

It is a cyclic number.

It is not a de Polignac number, because 21011099 - 2⁴ = 21011083 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21011009) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 617957 + ... + 617990.

It is an arithmetic number, because the mean of its divisors is an integer number (5561766).

Almost surely, 2^21011099 is an apocalyptic number.

21011099 is a deficient number, since it is larger than the sum of its proper divisors (1235965).

21011099 is a wasteful number, since it uses less digits than its factorization.

21011099 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1235964.

The product of its (nonzero) digits is 162, while the sum is 23.

The square root of 21011099 is about 4583.7865351694. The cubic root of 21011099 is about 275.9410143148.

It can be divided in two parts, 2 and 1011099, that added together give a palindrome (1011101).

The spelling of 21011099 in words is "twenty-one million, eleven thousand, ninety-nine".