21945043 has 2 divisors, whose sum is σ = 21945044. Its totient is φ = 21945042.

The previous prime is 21945029. The next prime is 21945067. The reversal of 21945043 is 34054912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21945043 - 2¹⁷ = 21813971 is a prime.

It is not a weakly prime, because it can be changed into another prime (21945023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10972521 + 10972522.

It is an arithmetic number, because the mean of its divisors is an integer number (10972522).

Almost surely, 2^21945043 is an apocalyptic number.

21945043 is a deficient number, since it is larger than the sum of its proper divisors (1).

21945043 is an equidigital number, since it uses as much as digits as its factorization.

21945043 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 21945043 is about 4684.5536607024. The cubic root of 21945043 is about 279.9704177931.

Adding to 21945043 its reverse (34054912), we get a palindrome (55999955).

The spelling of 21945043 in words is "twenty-one million, nine hundred forty-five thousand, forty-three".