21211399 has 8 divisors (see below), whose sum is σ = 23182992. Its totient is φ = 19247040.

The previous prime is 21211387. The next prime is 21211403. The reversal of 21211399 is 99311212.

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 21211399 - 2⁵ = 21211367 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211319) 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 7 ways as a sum of consecutive naturals, for example, 5707 + ... + 8659.

It is an arithmetic number, because the mean of its divisors is an integer number (2897874).

Almost surely, 2^21211399 is an apocalyptic number.

21211399 is a deficient number, since it is larger than the sum of its proper divisors (1971593).

21211399 is a wasteful number, since it uses less digits than its factorization.

21211399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3617.

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

The square root of 21211399 is about 4605.5834592373. The cubic root of 21211399 is about 276.8150963998.

It can be divided in two parts, 212113 and 99, that added together give a palindrome (212212).

The spelling of 21211399 in words is "twenty-one million, two hundred eleven thousand, three hundred ninety-nine".