21755143 has 2 divisors, whose sum is σ = 21755144. Its totient is φ = 21755142.

The previous prime is 21755141. The next prime is 21755159. The reversal of 21755143 is 34155712.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21755143 - 2¹ = 21755141 is a prime.

Together with 21755141, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21755141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10877571 + 10877572.

It is an arithmetic number, because the mean of its divisors is an integer number (10877572).

Almost surely, 2^21755143 is an apocalyptic number.

21755143 is a deficient number, since it is larger than the sum of its proper divisors (1).

21755143 is an equidigital number, since it uses as much as digits as its factorization.

21755143 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4200, while the sum is 28.

The square root of 21755143 is about 4664.2408814297. The cubic root of 21755143 is about 279.1605085248.

The spelling of 21755143 in words is "twenty-one million, seven hundred fifty-five thousand, one hundred forty-three".