21857648805 has 48 divisors (see below), whose sum is σ = 39021830640. Its totient is φ = 11309912064.

The previous prime is 21857648803. The next prime is 21857648809. The reversal of 21857648805 is 50884675812.

21857648805 is a `hidden beast` number, since 21 + 8 + 576 + 48 + 8 + 0 + 5 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 2297668356 + 19559980449 = 47934^2 + 139857^2 .

It is not a de Polignac number, because 21857648805 - 2¹ = 21857648803 is a prime.

It is a super-2 number, since 2×21857648805² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21857648803) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 569151 + ... + 606339.

It is an arithmetic number, because the mean of its divisors is an integer number (812954805).

Almost surely, 2^21857648805 is an apocalyptic number.

It is an amenable number.

21857648805 is a deficient number, since it is larger than the sum of its proper divisors (17164181835).

21857648805 is a wasteful number, since it uses less digits than its factorization.

21857648805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37590 (or 37587 counting only the distinct ones).

The product of its (nonzero) digits is 4300800, while the sum is 54.

The spelling of 21857648805 in words is "twenty-one billion, eight hundred fifty-seven million, six hundred forty-eight thousand, eight hundred five".