21168436 has 12 divisors (see below), whose sum is σ = 37104228. Its totient is φ = 10567232.

The previous prime is 21168409. The next prime is 21168439. The reversal of 21168436 is 63486112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 10278436 + 10890000 = 3206^2 + 3300^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21168398 and 21168407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21168439) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1201 + ... + 6616.

It is an arithmetic number, because the mean of its divisors is an integer number (3092019).

Almost surely, 2^21168436 is an apocalyptic number.

It is an amenable number.

21168436 is a deficient number, since it is larger than the sum of its proper divisors (15935792).

21168436 is a wasteful number, since it uses less digits than its factorization.

21168436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8498 (or 8496 counting only the distinct ones).

The product of its digits is 6912, while the sum is 31.

The square root of 21168436 is about 4600.9168651476. The cubic root of 21168436 is about 276.6280767454.

The spelling of 21168436 in words is "twenty-one million, one hundred sixty-eight thousand, four hundred thirty-six".