21081099 has 8 divisors (see below), whose sum is σ = 30270352. Its totient is φ = 12972960.

The previous prime is 21081061. The next prime is 21081101. The reversal of 21081099 is 99018012.

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

It is not a de Polignac number, because 21081099 - 2¹⁶ = 21015563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21081019) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 270232 + ... + 270309.

It is an arithmetic number, because the mean of its divisors is an integer number (3783794).

Almost surely, 2^21081099 is an apocalyptic number.

21081099 is a deficient number, since it is larger than the sum of its proper divisors (9189253).

21081099 is a wasteful number, since it uses less digits than its factorization.

21081099 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 540557.

The product of its (nonzero) digits is 1296, while the sum is 30.

The square root of 21081099 is about 4591.4157947195. The cubic root of 21081099 is about 276.2471138018.

The spelling of 21081099 in words is "twenty-one million, eighty-one thousand, ninety-nine".