21312277 has 16 divisors (see below), whose sum is σ = 24935040. Its totient is φ = 17839872.

The previous prime is 21312257. The next prime is 21312289. The reversal of 21312277 is 77221312.

It is a cyclic number.

It is not a de Polignac number, because 21312277 - 2⁷ = 21312149 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 (21312257) 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 15 ways as a sum of consecutive naturals, for example, 91353 + ... + 91585.

It is an arithmetic number, because the mean of its divisors is an integer number (1558440).

Almost surely, 2^21312277 is an apocalyptic number.

It is an amenable number.

21312277 is a deficient number, since it is larger than the sum of its proper divisors (3622763).

21312277 is a wasteful number, since it uses less digits than its factorization.

21312277 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 492.

The product of its digits is 1176, while the sum is 25.

The square root of 21312277 is about 4616.5221758376. The cubic root of 21312277 is about 277.2532319146.

Adding to 21312277 its reverse (77221312), we get a palindrome (98533589).

The spelling of 21312277 in words is "twenty-one million, three hundred twelve thousand, two hundred seventy-seven".