21161768 has 8 divisors (see below), whose sum is σ = 39678330. Its totient is φ = 10580880.

The previous prime is 21161761. The next prime is 21161779. The reversal of 21161768 is 86716112.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 21141604 + 20164 = 4598^2 + 142^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (21161761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1322603 + ... + 1322618.

Almost surely, 2^21161768 is an apocalyptic number.

It is an amenable number.

21161768 is a deficient number, since it is larger than the sum of its proper divisors (18516562).

21161768 is a wasteful number, since it uses less digits than its factorization.

21161768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2645227 (or 2645223 counting only the distinct ones).

The product of its digits is 4032, while the sum is 32.

The square root of 21161768 is about 4600.1921698990. The cubic root of 21161768 is about 276.5990279968.

The spelling of 21161768 in words is "twenty-one million, one hundred sixty-one thousand, seven hundred sixty-eight".