21118305857 has 16 divisors (see below), whose sum is σ = 23094099648. Its totient is φ = 19151911680.

The previous prime is 21118305827. The next prime is 21118305869. The reversal of 21118305857 is 75850381112.

It is not a de Polignac number, because 21118305857 - 2³² = 16823338561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21118305827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14736413 + ... + 14737845.

It is an arithmetic number, because the mean of its divisors is an integer number (1443381228).

Almost surely, 2^21118305857 is an apocalyptic number.

It is an amenable number.

21118305857 is a deficient number, since it is larger than the sum of its proper divisors (1975793791).

21118305857 is a wasteful number, since it uses less digits than its factorization.

21118305857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3760.

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

Adding to 21118305857 its reverse (75850381112), we get a palindrome (96968686969).

The spelling of 21118305857 in words is "twenty-one billion, one hundred eighteen million, three hundred five thousand, eight hundred fifty-seven".