21371772168 has 48 divisors (see below), whose sum is σ = 59446265580. Its totient is φ = 6931384704.

The previous prime is 21371772167. The next prime is 21371772187. The reversal of 21371772168 is 86127717312.

It can be written as a sum of positive squares in 2 ways, for example, as 18923303844 + 2448468324 = 137562^2 + 49482^2 .

It is not an unprimeable number, because it can be changed into a prime (21371772161) 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 11 ways as a sum of consecutive naturals, for example, 4008555 + ... + 4013882.

Almost surely, 2^21371772168 is an apocalyptic number.

It is an amenable number.

21371772168 is an abundant number, since it is smaller than the sum of its proper divisors (38074493412).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21371772168 is a wasteful number, since it uses less digits than its factorization.

21371772168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8022486 (or 8022479 counting only the distinct ones).

The product of its digits is 197568, while the sum is 45.

The spelling of 21371772168 in words is "twenty-one billion, three hundred seventy-one million, seven hundred seventy-two thousand, one hundred sixty-eight".