21936905 has 8 divisors (see below), whose sum is σ = 27232200. Its totient is φ = 16944256.

The previous prime is 21936883. The next prime is 21936907. The reversal of 21936905 is 50963912.

It can be written as a sum of positive squares in 4 ways, for example, as 5257849 + 16679056 = 2293^2 + 4084^2 .

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 21936905 - 2¹² = 21932809 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21936907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 75500 + ... + 75789.

It is an arithmetic number, because the mean of its divisors is an integer number (3404025).

Almost surely, 2^21936905 is an apocalyptic number.

It is an amenable number.

21936905 is a deficient number, since it is larger than the sum of its proper divisors (5295295).

21936905 is a wasteful number, since it uses less digits than its factorization.

21936905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151323.

The product of its (nonzero) digits is 14580, while the sum is 35.

The square root of 21936905 is about 4683.6849808671. The cubic root of 21936905 is about 279.9358058619.

The spelling of 21936905 in words is "twenty-one million, nine hundred thirty-six thousand, nine hundred five".