21755611 has 2 divisors, whose sum is σ = 21755612. Its totient is φ = 21755610.

The previous prime is 21755581. The next prime is 21755633. The reversal of 21755611 is 11655712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21755611 - 2⁵ = 21755579 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21755611.

It is not a weakly prime, because it can be changed into another prime (21755651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10877805 + 10877806.

It is an arithmetic number, because the mean of its divisors is an integer number (10877806).

Almost surely, 2^21755611 is an apocalyptic number.

21755611 is a deficient number, since it is larger than the sum of its proper divisors (1).

21755611 is an equidigital number, since it uses as much as digits as its factorization.

21755611 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2100, while the sum is 28.

The square root of 21755611 is about 4664.2910500954. The cubic root of 21755611 is about 279.1625102918.

It can be divided in two parts, 21755 and 611, that added together give a triangular number (22366 = T₂₁₁).

The spelling of 21755611 in words is "twenty-one million, seven hundred fifty-five thousand, six hundred eleven".