21857611543 has 2 divisors, whose sum is σ = 21857611544. Its totient is φ = 21857611542.

The previous prime is 21857611541. The next prime is 21857611577. The reversal of 21857611543 is 34511675812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21857611543 - 2¹ = 21857611541 is a prime.

Together with 21857611541, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21857611543.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21857611541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10928805771 + 10928805772.

It is an arithmetic number, because the mean of its divisors is an integer number (10928805772).

Almost surely, 2^21857611543 is an apocalyptic number.

21857611543 is a deficient number, since it is larger than the sum of its proper divisors (1).

21857611543 is an equidigital number, since it uses as much as digits as its factorization.

21857611543 is an evil number, because the sum of its binary digits is even.

The product of its digits is 201600, while the sum is 43.

The spelling of 21857611543 in words is "twenty-one billion, eight hundred fifty-seven million, six hundred eleven thousand, five hundred forty-three".