21857611541 has 2 divisors, whose sum is σ = 21857611542. Its totient is φ = 21857611540.

The previous prime is 21857611519. The next prime is 21857611543. The reversal of 21857611541 is 14511675812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20233924516 + 1623687025 = 142246^2 + 40295^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21857611541 is a prime.

Together with 21857611543, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21857611543) 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, 10928805770 + 10928805771.

It is an arithmetic number, because the mean of its divisors is an integer number (10928805771).

Almost surely, 2^21857611541 is an apocalyptic number.

It is an amenable number.

21857611541 is a deficient number, since it is larger than the sum of its proper divisors (1).

21857611541 is an equidigital number, since it uses as much as digits as its factorization.

21857611541 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 67200, while the sum is 41.

The spelling of 21857611541 in words is "twenty-one billion, eight hundred fifty-seven million, six hundred eleven thousand, five hundred forty-one".