21756433 has 2 divisors, whose sum is σ = 21756434. Its totient is φ = 21756432.

The previous prime is 21756431. The next prime is 21756457. The reversal of 21756433 is 33465712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19421649 + 2334784 = 4407^2 + 1528^2 .

It is a cyclic number.

It is not a de Polignac number, because 21756433 - 2¹ = 21756431 is a prime.

Together with 21756431, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21756395 and 21756404.

It is not a weakly prime, because it can be changed into another prime (21756431) 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 as a sum of consecutive naturals, namely, 10878216 + 10878217.

It is an arithmetic number, because the mean of its divisors is an integer number (10878217).

Almost surely, 2^21756433 is an apocalyptic number.

It is an amenable number.

21756433 is a deficient number, since it is larger than the sum of its proper divisors (1).

21756433 is an equidigital number, since it uses as much as digits as its factorization.

21756433 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15120, while the sum is 31.

The square root of 21756433 is about 4664.3791655482. The cubic root of 21756433 is about 279.1660261464.

The spelling of 21756433 in words is "twenty-one million, seven hundred fifty-six thousand, four hundred thirty-three".