21168407851 has 4 divisors (see below), whose sum is σ = 22282534600. Its totient is φ = 20054281104.

The previous prime is 21168407849. The next prime is 21168407867. The reversal of 21168407851 is 15870486112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21168407851 - 2¹ = 21168407849 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21168407798 and 21168407807.

It is not an unprimeable number, because it can be changed into a prime (21168407881) 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 3 ways as a sum of consecutive naturals, for example, 557063346 + ... + 557063383.

It is an arithmetic number, because the mean of its divisors is an integer number (5570633650).

Almost surely, 2^21168407851 is an apocalyptic number.

21168407851 is a deficient number, since it is larger than the sum of its proper divisors (1114126749).

21168407851 is a wasteful number, since it uses less digits than its factorization.

21168407851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1114126748.

The product of its (nonzero) digits is 107520, while the sum is 43.

The spelling of 21168407851 in words is "twenty-one billion, one hundred sixty-eight million, four hundred seven thousand, eight hundred fifty-one".