21642188543 has 2 divisors, whose sum is σ = 21642188544. Its totient is φ = 21642188542.

The previous prime is 21642188489. The next prime is 21642188549. The reversal of 21642188543 is 34588124612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21642188543 - 2¹⁶ = 21642123007 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21642188494 and 21642188503.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21642188549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10821094271 + 10821094272.

It is an arithmetic number, because the mean of its divisors is an integer number (10821094272).

Almost surely, 2^21642188543 is an apocalyptic number.

21642188543 is a deficient number, since it is larger than the sum of its proper divisors (1).

21642188543 is an equidigital number, since it uses as much as digits as its factorization.

21642188543 is an evil number, because the sum of its binary digits is even.

The product of its digits is 368640, while the sum is 44.

The spelling of 21642188543 in words is "twenty-one billion, six hundred forty-two million, one hundred eighty-eight thousand, five hundred forty-three".